Animal Science, Volume 81 - Issue 1 - August 2005
- This volume was published under a former title. See this journal's title history.
Animal Science
Editorial
Editorial
- Ian J. Lean
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- Published online by Cambridge University Press:
- 09 March 2007, p. 1
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The dog days of late July and early August, linked as they are in the northern hemisphere to the end of the undergraduate teaching year provide opportunity for those of us involved in university teaching to take stock of where we are in terms of courses, their development and their evaluation. Such seasonality is not quite so evident in editorial activities although there are blips in submission rates of manuscripts that reflect critical times in terms of grant completions and so on. Whatever the reasons we have time in these dog days to reflect on our activities. Among my recurrent thoughts as a journal editor at this time are the most recent ‘performance’ figures for Animal Science as demonstrated in the ISI journal citation reports and also perhaps the most exciting development in scientific publishing for many years, the advent of ‘open access’ to scientific papers.
Research Article
Feeding behaviour and diet choices and diet choices of cattle with physical and temporal constraints on forage accessibility: an indoor experiment
- C. Ginane, M. Petit
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- 09 March 2007, pp. 3-10
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An indoor choice experiment was conducted to assess the extent to which heifers offered two forages of different quality will attempt to consume the better quality forage when the weight/number of constraints applied on its harvesting increase. The experiment involved six Salers heifers, a leafy (L) and a coarse (C) hay, and two combined or single accessibility constraints. A physical constraint consisted of reducing the prehensibility of L by covering the trough with a steel grid of either 4 cm or 6 cm mesh size (L4 or L6 v. L ∞ for no grid). A temporal constraint limited the daily access time to both hays to 4 v. 24 h. The hays were either offered alone or together over 2-week periods. Dry-matter intake and feeding time were recorded daily.
As expected, the physical constraint (only L4 was efficient) made the heifers decrease their choice (proportion of feeding time or intake) for L regardless of access time, whereas the temporal constraint had no significant effect on choice. The heifers greatly modulated their intake rate of L even under strong physical constraint (L4), and then unexpectedly managed to ingest L faster than C. This emphasizes their motivation to keep ingesting the better quality forage, and underlines the difficulties in comparing diet choices with the optimal foraging theory predictions based on the relative values of a behavioural component subject to large variation, i.e. intake rate. In a very constraining situation (L4 and 4-h access), heifers made a choice that allowed them to increase their total daily digestible organic matter (DOM) intake compared with L4 or C offered alone because of an inverse relationship between feeding time and intake rate on L4. They did not however maximize their total daily DOM intake in a less constraining situation (L ∞ or L6 and C, with 4-h access), since they did not consume L exclusively and showed a marked preference for a mixed diet.
Genetic relationships between seasonal tissue levels in Scottish Blackface ewes and lamb growth traits
- N. R. Lambe, S. Brotherstone, M. J. Young, J. Conington, G. Simm
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- 09 March 2007, pp. 11-21
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Scottish Blackface ewes (no. = 308) were scanned four times per year using X-ray computed tomography (CT scanning) (pre-mating, pre-lambing, mid lactation and weaning), from 18 months to 5 years of age, giving a maximum of 16 scanning events per ewe. Total weights of carcass fat, internal fat and carcass muscle were estimated from the CT images at each scanning event. Lambs produced by these ewes were weighed at birth, mid lactation and weaning to calculate litter growth traits: litter birth weight; litter weight gain from birth until mid lactation; and litter weight gain from birth until weaning. Genetic (rg) and phenotypic (rp) correlations were estimated between ewe CT tissue traits and litter growth traits. Correlations between ewe CT tissue traits and litter size (LS) were also estimated. Ewe CT tissue traits were either unadjusted or adjusted for total soft tissue weight (sum of weights of carcass fat, internal fat and carcass muscle) to investigate relationships with either absolute tissue weights of carcass fat (CFWT), internal fat (IFWT), and carcass muscle (CMWT), or relative proportions of carcass fat (CFP), internal fat (IFP), and carcass muscle (CMP). Litter growth traits were either unadjusted or adjusted for litter size, to investigate relationships with total lamb burden (total litter birth weight (TBW), total litter weight gain from birth until mid lactation (TWGM), total litter weight gain from birth until weaning (TWGW)) or average lamb performance (average lamb birth weight (ABW), average lamb weight gain from birth until mid lactation (AWGM), average lamb weight gain from birth until weaning (AWGW)).
Moderate to large positive genetic correlations were estimated between absolute weights of all three ewe tissues (CFWT, IFWT, CMWT), or muscle proportion (CMP), and litter size (LS). Significant positive genetic correlations were also estimated between weight (CMWT) or proportion (CMP) of muscle carried by the ewe pre-mating and total birth weight (TBW) and weight gains (TWGM, TWGW) of her litter, largely due to the associated increase in litter size. Muscle proportion (CMP) was not significantly correlated to average lamb weights or weight gains (ABW, AWGM, AWGW). Pre-lambing carcass fat weight (CFWT) and proportion (CFP) in the ewe showed positive genetic correlations with average lamb weights and weight gains (ABW, AWGM, AWGW), whereas, after lambing, CFP was negatively correlated with these lamb traits. Internal fat weight (IFWT) pre-mating showed positive genetic correlations with all litter growth traits (TBW, TWGM, TWGW, ABW, AWGM, AWGW). Average lamb growth traits were negatively correlated with pre-lambing internal fat proportion (IFP), but positively correlated to IFP at mid lactation and weaning.
Correlations were also estimated between each pair of CT traits. Total internal fat weight and total carcass fat weight were very highly correlated (rp = 0·75, rg = 0·96). Correlations with total carcass muscle weight were smaller and positive for both carcass fat weight (rp = 0·48, rg = 0·12) and internal fat weight (rp = 0·42, rg = 0·20).
The results suggest that selection for increased carcass muscle weight or proportion in a Scottish Blackface hill flock would have a positive effect on total weights of litters reared, but that selection against carcass fat weight or proportion in a breeding programme for Blackface sheep may have an impact on the maternal ability of the ewe. However, maintaining fat in internal depots may reduce the depletion of carcass fat during pregnancy, allowing this depot to provide energy for lactation, and may have a positive impact on lamb growth.
Costs of the major endemic diseases of sheep in Great Britain and the potential benefits of reduction in disease impact
- G. J. Nieuwhof, S. C. Bishop
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- 09 March 2007, pp. 23-29
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The costs of three major endemic sheep diseases in Great Britain, gastro-intestinal (GI) parasites, footrot and scab, were estimated and compared with costs for other diseases from another study. Disease costs include lost performance, preventive measures and treatment of affected animals. The most costly disease, of those studied, for the British sheep industry is infestation with GI parasites, with estimated annual costs of £84 million. Annual costs for the other two diseases are £24 million for footrot and £8 million for sheep scab. This compares with literature estimates of £20 million for Chlamydial abortions and £12 million for toxoplasmosis. For sheep scab most costs are for preventive measures, therefore, short of eradication, a reduction in incidence will have a limited effect on costs. For GI parasites, costs are linearly related to the severity of the infestation and a reduction of the disease will have a proportional effect on the costs to the industry. For footrot about half the costs are for preventive measures, the other half is for lost production and treatment. A reduction in the incidence of footrot has a proportional effect on the £10 million associated with loss of production and treatment of infected animals. It is concluded that gastro-intestinal parasites and footrot are two sheep diseases in Britain for which a reduction of severity or incidence will have a large impact on costs of production.
In vitro microbial growth and rumen fermentation of different substrates as affected by the addition of disodium malate
- M. L. Tejido, M. J. Ranilla, R. García-Martínez, M. D. Carro
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- 09 March 2007, pp. 31-38
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The effects of two concentrations of disodium malate on the in vitro fermentation of three substrates differing in their forage: concentrate ratio (0·8: 0·2, 0·5: 0·5 and 0·2: 0·8; g/g dry matter; low-, medium- and high-concentrate substrates, respectively) by rumen micro-organisms were studied using batch cultures. Rumen contents were collected from four Merino sheep offered lucerne hay ad libitum and supplemented daily with 400 g concentrate. Disodium malate was added to the incubation bottles to achieve final concentrations of 0, 4 and 8 mmol/l malate and 15N was used as a microbial marker. Gas production was measured at regular intervals from 0 to 120 h of incubation to study fermentation kinetics. When gas production values were corrected for gas released from added malate, no effects (P > 0·05) of malate were detected for any of the estimated gas production parameters. In 17-h incubations, the final pH and total volatile fatty acid (VFA) production were increased (P < 0·001) by the addition of malate, but no changes (P > 0·05) were detected in the final amounts of ammonia-N and lactate. When net VFA productions were corrected for the amount of VFA produced from malate fermentation itself, adding malate did not affect (P > 0·05) the production of acetate, propionate and total VFA. Malate reduced methane (CH4) production by proportionately 0·058, 0·013 and 0·054 for the low-, medium- and high-concentrate substrates, respectively. Adding malate to batch cultures increased (P < 0·01) rumen microbial growth (mean values of 16·6, 18·3 and 18·4 mg of microbial N for malate at 0, 4 and 8 mmol/l, respectively), but did not affect (P > 0·05) its efficiency of growth (55·5, 56·7 and 54·3 mg of microbial N per g of organic matter apparently fermented for malate at 0, 4 and 8 mmol/l, respectively). There were no interactions (P > 0·05) malate × substrate for any of the measured variables, and no differences (P > 0·05) in pH, CH4 production and microbial growth were found between malate at 4 and 8 mmol/l. The results indicate that malate had a beneficial effect on in vitro rumen fermentation of substrates by increasing VFA production and microbial growth, and that only subtle differences in the effects of malate were observed between substrates. Most of the observed effects, however, seem to be due to fermentation of malate itself.
Metabolic response of pigs supplemented with incremental levels of leguminous Acacia karroo, Acacia nilotica and Colophospermum mopane leaf meals
- T. E. Halimani1, L. R. Ndlovu, K. Dzama, M. Chimonyo, B. G. Miller
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- 09 March 2007, pp. 39-45
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The nutritional effects of varying levels of leguminous leaf meal inclusion were investigated using 40 mixed weaner pigs of average weight 31·4 (s.d. 4·19) kg offered diets which included leguminous leaf meals (Acacia karroo, Acacia nilotica and Colophospermum mopane) over 18 days. The leaf meals were included at 100, 200 and 300 g/kg of dry matter. Leaf meals increased daily live-weight gain (P > 0·05) at low inclusion levels. They were also shown to increase food intake and food conversion ratio. There was an increase in digestibility of dry matter and protein at low inclusion level of leaf meals (P < 0·05), then a decrease in the digestibility as the level of leaf meals increased. Inclusion of leaf meals induced production of proline-rich proteins (molecular weights of 24 600, 54 000, 66 000 and 74 000 Da) in the parotid salivary glands of pigs but not in the mandibular glands (P > 0·05). The activity of hepatic microsomal uridine diphosphate glucuronyl transferase increased significantly (P < 0·05) for pigs offered diets supplemented with A. nilotica and C. mopane but not with A. karroo (P < 0·05). Intestinal parameters (crypt depth, villus height and villus-crypt ratio) were not significantly affected by leaf meal inclusion (P > 0·05) except crypt depth at the proximal position of the small intestine, which decreased with increasing leaf meal levels (P < 0·05).
Estimation of roughage intake in sheep using a known daily intake of a labelled supplement
- C. Elwert, H. Dove
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- 09 March 2007, pp. 47-56
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A feeding trial with growing sheep was conducted on mixed roughage-supplement diets, to test whether roughage intake could be estimated from a known intake of a supplement and an alkane-based estimate of the supplement and roughage proportions in the diet (diet composition) without the need for separate dosing with external marker alkanes. Diets consisted of chaffed Trifolium subterraneum hay (SC), or a mix of SC and beeswax-labelled cottonseed meal (CSM) in the proportions of 7: 1, 6: 2, 5: 3 and 4: 4 (air-dry matter basis). Six sheep were given the pure SC diet and three sheep were given each of the mixed diets. Additionally, the CSM was also labelled with octatriacontane (C38) to investigate its use for labelling supplements. Due to unexpectedly low recoveries, C38 was not included in any estimation of diet composition or digestibility.
The inclusion of beeswax-labelled CSM in a SC diet resulted in lower faecal alkane recoveries (as proportions of alkane ingested; P ≤ 0·05). Within mixed diets, recoveries decreased significantly with increasing proportion of CSM, but this effect was significant (P < 0·05) only for alkanes consisting of 25, 26, 27 and 29 carbon-atoms. Estimates of diet composition were close to measured values. Daily SC intake and organic matter digestibility (OMD) differed by −3·7 to 7·2% and −2·0 to 5·7% from measured values if a mean faecal recovery, across diets, was applied for each alkane. Accuracy increased greatly if estimates were based upon faecal alkane recoveries for individual diets, instead of mean recoveries across diets (−0·3 to 0·9% and −0·2 to 0·0% for SC intake and OMD, respectively).
The results indicate that roughage intake can be estimated from a combination of known supplement intake and an estimate of diet composition, which obviates the need for separate alkane dosing to estimate intake. The method should be applicable in situations in which animals either normally receive supplements (e.g., dairy cows) or could readily be given supplements.
Validation of use of purine bases as a microbial marker by 15N labelling in growing lambs given high-concentrate diets: effects of grain processing, animal age and digesta sampling site
- A. R. Askar, J. A. Guada, J. Balcells, A. de Vega, C. Castrillo
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- 09 March 2007, pp. 57-65
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The origin of post-ruminal purine bases (PB) was studied in 24 growing lambs that were given a pelleted concentrate plus barley straw (C) or whole barley grain plus protein supplement (WB). Six lambs from each treatment were slaughtered at 10 and 30 days post weaning after 15N labelling of microbial nitrogen (N) and PB. Microbial contribution to digesta non-ammonia N (NAN) and PB was lower (P < 0·01) when estimated from duodenal rather than abomasal samples (0·36 v. 0·52 (s.e.d. 0·021) for NAN and 0·47 v. 0·77 (s.e.d. 0·029) for PB) as a result of endogenous contamination. In comparison with 15N, total PB/N led to higher estimates (P < 0·01) of microbial contribution to abomasal NAN in WB treatment (0·62 v. 0·46 s.e.d. 0·049). The difference was removed after correcting for microbial PB, while this effect was not observed with < the C diet, resulting in a marker by diet interaction (P < 0·05). Abomasal PB flow increased (P < 0·1) from 10 to 30 days after weaning mainly due to the higher proportion of microbial PB (0·70 v. 0·81 (s.e.d. 0·047)). Rumen apparent PB degradation did not differ between diets in older lambs, but it was proportionally 0·39 lower for WB treatment (P < 0·05) in younger lambs. When the microbial PB flow was estimated indirectly from labelled microbial N and the PB/N ratio of bacterial extracts the estimates were in agreement with those derived from PB-15N in the WB treatment but resulted in unrealistic values in lambs on diet C. Results suggest that significant proportions of dietary PB can escape rumen degradation which may lead to overestimation of microbial contribution to abomasal NAN when the PB/N ratio is used as marker. The extent of the overestimation is affected by the lamb age and grain processing.
Effect of phytase supplementation with two levels of phosphorus diets on ileal and faecal digestibilities of nutrients and phosphorus, calcium, nitrogen and energy balances in growing pigs
- M. Z. Fan, T. J. Li, Y. L. Yin, R. J. Fang, Z. Y. Tang, Z. P. Hou, R. L. Huang, Z. Y. Deng, H. Y. Zhong, R. G. Zhang, J. Zhang, B. Wang, H. Schulze
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- 09 March 2007, pp. 67-75
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The experiment was conducted to assess the effects of phytase supplementation to diets with two levels of phosphorus (P) on ileal and faecal digestibility of nutrients and phosphorus, calcium, nitrogen and energy balances in growing pigs. Fifteen Landrace × Large White × Chinese Black barrows, with an initial live weight of 22·2 kg fitted with a simple T-cannula at the distal ileum, were randomly allocated to one of the five diet treatments, according to a of cross-over design with two periods. The basal diet was typical of southern Asia with maize/rice and rapeseed/cottonseed meals. A normal (NP, supplemented with 4·8 g/kg of CaHPO4) and a low-P diet (LP, not supplemented with CaHPO4) were formulated. Both of the diets were supplemented with and without Natuphos® Phytase (500 phytase units (FTU) per kg diet). An enzyme hydrolysed casein (EHC) diet (diet 5) was also formulated to determine the flow of the ileal endogenous amino acids (AA). The results showed that both the higher level P treatment and phytase supplementation increased (P < 0·05) the apparent ileal digestibility (AID) of dry matter (DM), organic matter (OM), crude protein (CP) and energy. Phytase supplementation also increased (P < 0·05) the AID of Ca and P. Pigs given the higher level of P or the phytase diet increased apparent faecal digestibility (AFD) of DM, OM and energy. Phytase supplementation reduced (P < 0·01) faecal Ca output and increased (P < 0·05) proportional Ca retention. The higher level of P increased (P < 0·001) total P intake and P retention (P < 0·05) but did not affect the proportion of P retained (P > 0·05). Phytase supplementation did not affect P balance (P > 0·05). Pigs given the higher level P or the phytase diet had reduced (P < 0·05) faecal energy concentration, although there was no affect on urine energy output, digestible energy (DE) and metabolizable energy (ME). However, there were P × phytase effects on DE and ME (P < 0·05). There were no P × phytase effects (P > 0·05) on AID of AA except with isoleucine (P < 0·01). Phytase supplementation increased (P < 0·05) AID of histidine, isoleucine, threonine and glutamine and there was a numeric increase in AID for most of the other AA. There was P × phytase effect on AFD of histidine (P < 0·05), isoleucine (P < 0·05), methionine (P < 0·05) and threonine (P < 0·01). Phytase supplementation increased the AFD of isoleucine (P < 0·05), threonine (P < 0·01) and tended to increase AFD of tyrosine (P < 0·05). The level of MCP affected the AFD of lysine (P < 0·01), threonine (P < 0·05), aspartic acid (P < 0·05). Phytase supplementation increased true ileal digestibility of histidine (P < 0·05), isoleucine (P < 0·001), threonine (P = 0·001), glutamine (P < 0·01), respectively. These results indicate that phytase used in the present study was able to improve the utilization of DM, OM, CP, Ca, P, energy and amino acid in a maize/rice and rapeseed/cottonseed meal based diet and reduce total output of them in manure.
Replacement of zinc sulphate by microbial phytase for piglets given a maize-soya-bean meal diet
- C. Jondrevillea, R. Hayler, D. Feuerstein
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- 09 March 2007, pp. 77-83
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Forty-eight pigs, weaned at 27 days of age at an average body weight of 7·55 kg were used in a 19-day experiment to investigate the influence of microbial phytase on zinc utilization and to calculate equivalency values of zinc as sulphate for microbial phytase. Eight experimental diets were formulated: a maize-soya-bean meal basal diet containing 30 mg of zinc per kg supplemented with 10, 25, 40 or 100 mg of zinc from sulphate (ZnSO4, 7H2O) per kg or with 100, 250, 500 or 750 units (U) of microbial phytase (3- phytase from Aspergillus niger, Natuphos ®) per kg. The dietary supplies of calcium and phosphorus were adjusted accounting for the release of these elements by microbial phytase. The copper concentration in the diets was 11 mg/kg. Pigs were given the basal diet for a 7-day adjustment period prior to the 19-day experimental period. At the end of the experiment, bone ash, phosphorus and calcium concentrations as well as plasma and liver copper concentrations were independent of the diet (P > 0·10). The zinc status of piglets was assessed through plasma alkaline phosphatase activity (APA) and zinc concentration, bone zinc concentration and liver zinc concentration. Plasma zinc, plasma APA and bone zinc increased linearly (P < 0·001) and quadratically (P < 0·01, P < 0·001 and P < 0·001, respectively) with zinc added. These parameters also increased linearly (P < 0·001) and quadratically (P < 0·05, P < 0·001 and P < 0·05, respectively) with phytase added. Liver zinc increased quadratically (P < 0·05) with zinc added and tended to increase linearly with phytase added (P = 0·077). Linear and non-linear response equations of indicators of zinc status to zinc added and phytase added were developed and used to calculate zinc equivalency values of phytase. Non-linear models were linear plateau models for zinc added and exponential models for phytase added. Plasma APA, plasma zinc and bone zinc were maximized when zinc added reached 43, 54 and 56 mg/kg of diet, respectively. The mean function of equivalency of zinc as sulphate (Zn, mg/kg of diet) for microbial phytase (Phyt, U per kg of diet) was Zn = 49·9 − 58·3 e−0·00233Phyt. From this equation it is calculated that 250, 500, and 750 U of 3-phytase from Aspergillus niger can avoid the addition of 17, 32 and 40 mg of zinc as sulphate in a piglet diet. Zinc ingested and, in turn, zinc excreted, may be proportionately reduced by almost 0·30 by replacing 30 mg of zinc as sulphate by 500 U of phytase as Natuphos ® in a piglet maize and soya-bean meal diet formulated to contain 100 mg of zinc per kg.
Apparent ileal digestibility of amino acids in dietary ingredients for broiler chickens
- V. Ravindran, L. I. Hew, G. Ravindran, W. L. Bryden
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- 09 March 2007, pp. 85-97
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The apparent ileal digestibility coefficients of amino acids in 107 samples representing 22 food ingredients were determined using 6-week-old broiler chickens. The ingredients assayed included five cereals (barley, maize, sorghum, triticale and wheat), two cereal by-products (rice polishings and wheat middlings), four oilseed meals (canola, cottonseed, soya-bean and sunflower meals), full-fat canola, maize gluten meal, four grain legumes (chickpeas, faba beans, field peas and lupins) and five animal protein sources (blood, feather, fish, meat and meat and bone meals). The mean ileal digestibility coefficients of amino acids in wheat and maize were higher than those in sorghum, triticale and barley. However, variations observed in individual amino acid digestibilities among samples within cereal type were greater than those determined between cereals. Threonine and lysine were the least digestible indispensable amino acids in the five cereals evaluated. The most digestible indispensable amino acid was phenylalanine in wheat and, leucine in maize and sorghum. In the case of the wheat middlings and rice polishings, threonine was the least digestible indispensable amino acid and arginine was the best digested.
In the oilseed meals assayed, amino acid digestibility was highest for soya-bean and sunflower meals, intermediate for canola meal and lowest for cottonseed meal. Ileal digestibility coefficients of amino acids in lupins were found to be slightly lower than those in soya-bean meal. The amino acid digestibilities of field peas, faba beans and chickpeas were considerably lower than those of lupins. Digestibility of arginine was the highest and that of threonine was the lowest of the indispensable amino acids in oilseed meals and grain legumes, except in cottonseed meal. Lysine was the least digestible amino acid in cottonseed meal.
In the animal protein sources assayed, digestibility coefficients of amino acids in blood meal were high, intermediate in fish meal, and low in meat meal, meat and bone meal and feather meal. Variation in amino acid digestibility coefficients determined for blood meal samples was small. However, wide variations in amino acid digestibilities were observed for other animal protein sources, highlighting significant batch-to-batch differences. In particular, marked variations were determined for meat meal and meat and bone meal samples. Cystine was the least digested amino acid in animal protein meals, with the exception of blood meal in which isoleucine had the lowest digestibility. The limitations of using apparent digestibility values in diet formulations and the concept of the standardized digestibility system to overcome these limitations are discussed.
Effect of drinking saline water on food and water intake, food digestibility, and nitrogen and mineral balances of rusa deer stags (Cervus timorensis russa)
- W. Yape Kii, G. McL. Dryden
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- 09 March 2007, pp. 99-105
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The salinity tolerance of Javan rusa deer (Cervus timorensis russa) was investigated with seven stags, aged 4·5 years. Animals were offered a medium-quality chaffed lucerne hay and given five different levels of water salinity: (a) control (570 mg/kg of total dissolved salts (TDS)) and (b) ‘saline’ water with TDS contents of 1000, 3500, 6000 and 8500 mg/kg. Food intake, food digestibility and nitrogen balance were not affected by increasing salt concentration in drinking water, however the drinking water (DW) intake, the total (food plus drinking) water intake and the DW:dry-matter ratio increased with increasing salt concentration. Some deer given water containing 8500 mg TDS per kg showed signs of stress which included large between-day fluctuations in water intake, opening of the orbital gland, head shaking, and rapid breathing. Rusa deer can tolerate drinking water containing 6000 mg TDS per kg for at least 9 days without harmful effect but may be unable to tolerate water with 8500 mg TDS per kg.
Accumulation of potentially toxic metals in the liver tissue of sheep grazed on sewage sludge-treated pastures
- S. M. Rhind, C. E. Kyle, J. Owen
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- 09 March 2007, pp. 107-113
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Concentrations of potentially toxic metals (PTMs) in the livers of pregnant, mature ewes and their 110 day foetuses, and in 6-month old lambs born to other ewes, were determined. The animals had been reared on pastures fertilized for 5 years with either sewage sludge (treated; T) or conventional inorganic fertilizer (control; C). The effects of treatment on patterns of accumulation of PTMs differed with stage of development and with individual PTM. In the liver of lambs, concentrations of Pb were elevated in T compared with C liver (P < 0·01), while Cu and Zn were lower (P < 0·001) in T than C liver. By contrast, in ewe liver, Cu concentrations were lower in T than C liver (P < 0·05), as in lambs, but there were no other treatment differences in PTM concentration. Ewe and lamb tissue data were not directly comparable because they were exposed to different diets but mean concentrations of Cd, Ni and Pb were approximately two- to four-fold higher in ewe than lamb liver while mean Cu concentrations were approximately five-fold lower, suggesting that more prolonged exposure to PTMs may have enhanced treatment differences in tissue PTM concentrations. Mean foetal PTM concentrations were not significantly affected by treatment. It is concluded that the repeated application of sludge to pasture is associated with altered, but not necessarily increased, rates of accumulation of PTMs in liver tissue, that rates of accumulation depend on the individual PTM measured and that they are probably influenced by duration and route of exposure and source of nutrient. Limited observations suggested that there was little effect of year, and associated variation in climatic conditions and herbage growth, on PTM accumulation.
Tolerance of imported rabbits grown as meat animals to hot climate and saline drinking water in the subtropical environment of Egypt
- I. F. M. Marai, A. A. M. Habeeb, A. E. Gad
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- 09 March 2007, pp. 115-123
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Ninety of each of New Zealand White (NZW) and Californian (Cal) male weaned rabbits at 5 weeks of age with nearly similar average live weights were used during two periods of the year (mild and hot, each of 9 weeks), in a trial to evaluate their adaptability as meat animals to the subtropical conditions of Egypt. The results showed that NZW surpassed Cal, in most of the traits studied. The increase was significant in final live weight, daily weight gain, final body solids, daily body solids gain, body water concentration (ml per 100 g body solids) and pre-slaughter weight. Meanwhile, Cal significantly surpassed NZW in daily water consumption. The temperature-humidity index (THI) values indicated absence of heat stress in the first period and exposure to moderate (but very close to severe) heat stress in the second. The hot conditions induced significant decline in final live weight, daily weight gain, food intake, final body solids, daily body solids gain, plasma tri-iodothyronine (T3) hormone, total proteins, albumin, globulin, total lipids, glucose, electrolytes (Na, K, Ca, Mg and P), pre-slaughter weight and kidneys with fat weight. In contrast, the hot conditions were accompanied by significant increases in water intake, body water concentration, plasma urea-N, creatinine and physiological body reactions (respiration rate and temperatures of rectum, skin and ear). Drinking water containing high levels of salt (3000 p. p. m. and more) caused significant decreases in final live weight, daily live-weight gain, final body solids, daily body solids gain, plasma T3 hormone, total proteins, albumin, total lipids, glucose, pre-slaughter weight and kidneys with fat weight. At the same time, significant increases occurred in water consumption, body water concentration, plasma urea-N, creatinine, electrolytes (Na, K, Ca and P), respiration rate and rectal and skin temperatures. Estimations of adaptability to the subtropical environment of Egypt and tolerance to drinking saline water under the same conditions were found to be proportionately 0·844 and 0·876 and 0·821 and 0·803, in NZW and Cal, respectively.
Ileal digestibility of raw and autoclaved kidney-bean (Phaseolus vulgaris) seed meals in cannulated pigs
- L. A. Rubio
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- 09 March 2007, pp. 125-133
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Five castrated male pigs (100±2 kg mean live weight) fitted with T-shaped ileal cannulae were used to determine ileal digestibility of raw or autoclaved (136°C, 3 min, 2·3 bar) kidney-bean seed meals, which were included (536 g/kg) in the diet as the only protein source. A protein-free and a diet based on hydrolysed casein were used to estimate endogenous protein secretion. Apparent ileal digestibility of dry matter was lower (P < 0·05) for raw compared to autoclaved kidney-bean meal. Apparent and true ileal digestibilities of raw kidney-bean meal were not only lower (P < 0·05) than those of autoclaved kidney beans, but negative or close to zero for N and some amino acids. Ileal N (36·9 g/kg food ingested) and sialic acid (3·5 g/kg food ingested) flows in pigs given the raw kidney-bean-based diet were higher (P < 0·05) than those of pigs given the autoclaved kidney-bean diet (respectively 8·9 and 1·4 g/kg food ingested). Autoclaved kidney beans contained 364 and 143 g/kg of starch and non-starch polysaccharides respectively, the ileal digestibilities of which were 0·79 and 0·26. Among individual non-starch polysaccharide sugars, apparent ileal digestibility values were between 0 (rhamnose) and 0·38 (arabinose). Ileal apparent digestibility of total oligosaccharides in the autoclaved kidney bean diet was 0·52, and total amounts of oligosaccharides digested was 18·6 g/kg food. Among individual short-chain fatty acids in ileal contents, only propionate values were signifi cantly (P < 0·05) different between pigs given raw or autoclaved kidney-bean diets. Lactate concentration in ileal contents was higher (P < 0·05) in pigs given autoclaved compared with raw kidney beans. Ileal digestibility of autoclaved kidney-bean meal in the 10-kg pigs was poorer than that of other raw legume-seed meals such as lupins and chickpeas in other studies. The potential health implications of these results are also discussed.
Effect of nucleotide supplementation on lymphocyte DNA damage induced by dietary oxidative stress in pigs
- J. Salobir, V. Rezar, T. Pajk, A. Levart
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- 09 March 2007, pp. 135-140
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The aim of the present study was to evaluate the effect of nucleotide supplementation on the oxidative stress induced by a high proportion of dietary polyunsaturated fatty acids ( PUFAs) in pigs. Twenty-four male growing pigs were penned individually and after an adaptation period divided into three groups. All groups received isocaloric daily rations composed of a basal diet supplemented with either: starch (CONT), linseed oil (LIN) and LIN and nucleotides (LIN + NUC). The experimental period lasted 21 days. Oxidative stress was evaluated by measuring the degree of lymphocyte nuclear DNA damage, the urine malondialdehyde ( MDA) excretion rate, erythrocyte glutathione peroxidase concentration and the total anti-oxidant status of plasma. Malondialdehyde concentrations in the blood and MDA urinary excretion rates were higher (P < 0·01) in animals supplemented with LIN and LIN + NUC compared with CONT animals. The degree of DNA damage in the LIN-supplemented animals was also higher (P < 0·01). Compared with the LIN-supplemented animals, nucleotide supplementation reduced (P < 0·01) the degree of DNA damage in lymphocytes to the level of the CONT group. Erythrocyte glutathione peroxidase concentration and plasma total anti-oxidant status were similar across treatments. The results of this experiment indicate that nucleotide supplementation effectively eliminates the genotoxic effects of high PUFA intakes on blood lymphocytes and demonstrates new evidence for the immunonutritive effect of nucleotides.
Comparative apparent total tract digestibility of major nutrients and amino acids in dogs (Canis familiaris), blue foxes (Alopex lagopus) and mink (Mustela vison)
- S. G. Vhile, A. Skrede, Ø. AhlstrØm, K. Hove
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- 09 March 2007, pp. 141-148
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Major nutrient and amino acid digestibilities were evaluated in experiments with dogs (Canis familiaris), blue foxes (Alopex lagopus) and mink (Mustela vison) using seven extruded diets containing different protein sources. Four dogs (German shepherd), four blue foxes and four mink were offered each of the experimental diets to determine apparent total tract digestibility. Average digestibility of crude protein (CP) in blue foxes and mink was similar, and lower than the corresponding value in dogs (0·834 and 0·831 v. 0·864) (P < 0·001). CP digestibility in blue foxes showed significant correlations with dogs and mink (P < 0·05), while no significant correlation was observed between dogs and mink. Average digestibility of most amino acids was significantly lower in blue foxes than in dogs (P < 0·001), whereas mink digested most essential amino acids at the same level as did dogs. Most non-essential amino acids were digested at a significantly lower rate in the mink than in the dog and the blue fox (P < 0·001). There were significant correlations in the digestibility of most amino acids between dogs and blue foxes, and between blue foxes and mink (P < 0·05). Correlations were significant between dogs and mink for the digestibility of most essential amino acids (P < 0·05) but not significant (P > 0·05) for several non-essential amino acids. Average digestibility of crude fat was high and similar among the species studied: 0·968, 0·967 and 0·959 in dogs, blue foxes and mink, respectively. Average digestibility of starch ranged from 0·971 in mink to 0·998 in dogs; significantly higher in dogs than in blue foxes and mink, and significantly higher in blue foxes than in mink (P < 0·001). It was concluded that digestibility determined with mink, blue foxes or dogs may be used to predict digestibilities in the other investigated species. However, both the characteristics of the protein sources as well as the individual amino acid studied will influence the difference in digestibility among the species.
Biochemical differences in Merino sheep selected for resistance against gastro-intestinal nematodes and genetic and nutritional effects on faecal worm egg output
- S. M. Liu, T. L. Smith, D. G. Palmer, L. J. E. Karlsson, R. B. Besier, J. C. Greeff
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- 09 March 2007, pp. 149-157
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The faecal egg count (FEC) and total egg output is reduced in parasite-resistant sheep and breeding sheep for resistance should reduce infective larval contamination of pastures. This research compares lambs and rams from the parasite-resistant flock, Rylington Merinos, with unselected controls at the same level of larval challenge and the same level of food supply in an animal-house environment. The sheep were penned individually. The parasite resistant sheep excreted 0·85-fold less eggs than the control animals after infection with Trichostrongylus colubriformis and Ostertagia circumcincta for 12 or 18 weeks. During the infection period the parasite resistant lambs had higher plasma immunoglobulin concentration and higher ratio of globulin to albumin than the control animals. In the mature rams these genotype differences diminished. They also had lighter mass of the small intestine with a higher proportion of mucosa, but heavier mass of the large intestine. Parasite infection caused a depletion of blood glutathione in the lambs given food at maintenance or 1·5 × maintenance, and the parasite-resistant sheep (both lambs and rams) also had lower glutathione concentration. Maintaining good body nutrient reserve before the infection reduced the egg output in the early stage of the infection. Food intake had little effect on worm egg production in young sheep given food at maintenance or above. It is suggested that an improvement of nutrition, sulphur-containing amino acids in particular, is required to recover the loss of productive performance caused by the infection.
Intake, growth and meat quality of steers given diets based on varying proportions of maize silage and grass silage
- D. T. Juniper, E. M. Browne, A. V. Fisher, M. J. Bryant, G. R. Nute, D. E. Beever
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- 09 March 2007, pp. 159-170
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Simmental × Holstein-Friesian steers were offered four forage diets. These comprised grass silage (G); proportionately 0·67 grass silage, proportionately 0·33 maize silage (GGM); 0·33 grass silage, 0·67 maize silage (MMG); maize silage (M) from 424 (s.d. = 11·5) kg to slaughter at a minimum weight of 560 kg. Forages were mixed and offered ad libitum. Steers were offered 2 kg of a concentrate daily, the concentrate being formulated such that all steers had similar crude protein intakes across dietary treatments. A sample of steers was slaughtered at the beginning of the experimental period to allow the calculation of the rate of gain of the carcass and its components. Carcass dissection of a sample of steers allowed the development of a prediction equation of carcass composition based on thoracic limb dissection of all carcasses. Forage dry matter intake and live-weight gain increased linearly as maize silage replaced grass silage in the forage mixture, resulting in improvements in food conversion ratio (all P = 0·001). Killing-out proportion increased with maize silage inclusion (P < 0·001) but fat and conformation scores did not differ significantly between diets. However, increasing maize inclusion in the diet resulted in a greater weight (P = 0·05) and proportion (P = 0·008) of fat in the carcass, and significant increases in internal fat deposition. The inclusion of maize led to a progressive increase in the daily gains of carcass (P < 0·001), and significant increases in the daily gains of both fat (P < 0·001) and lean tissue (P < 0·001). Fat colour was more yellow in cattle given diets G and GGM than diets MMG and M(P < 0·001) and colour intensity was lower on diet M than the other three diets (P < 0·001). There were no significant differences in any aspects of eating quality between diets. Therefore, maize silage has the potential to reduce the time taken for finishing beef animals to achieve slaughter weight with no apparent detrimental effects on subsequent meat quality.
Management strategies to maximize pigmeat output: effect of group size and split-marketing
- M. K. O'Connell, P. B. Lynch, J. V. O'Doherty
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- 09 March 2007, pp. 171-177
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Two experiments were completed with grower-finisher pigs to determine if pigmeat output, as measured by carcass gain per m2 per year, could be increased, by 1: increasing group size or 2: split-marketing pen groups. In experiment 1, 390 pigs (mean initial live weight 36·7 (s.d. 1·99) kg) were assigned to one of three treatments each with 10 replicates: 11, 13 or 15 pigs per single-sex group in pens measuring 11·04 m2. Space allowance was 1·00, 0·85 and 0·74 m2 per pig, respectively. Pelleted food was provided ad libitum. There were no differences (P > 0·05) between group sizes in growth rate, food intake, food conversion ratio, carcass growth and carcass food conversion ratio, backfat and muscle depth or carcass lean content. Pigmeat output per unit area increased with each increase in group size (234, 279 and 314 kg/m2 per year for 11, 13 and 15 pigs: P < 0·001). In experiment 2, 26 groups of 13 pigs (mean initial live weight 38·3 (s.d. 2·15) kg) were assigned to one of three treatments: 1D - group sold on 1 day (no. = 9), 2D - group sold over 2 days (14 days apart, no. = 10), or 3D - group sold over 3 days (each 7 days apart, no. = 7). Pigs were given a standard liquid diet three times daily. No differences (P > 0·05) were observed between treatments for overall growth rate, food intake, food conversion ratio, carcass weight, carcass lean content, backfat and muscle depth, carcass growth and carcass food conversion ratio or killing-out proportion of pigs. Split-marketing increased cycle length (67·7, 75·9 and 76·8 days for 1D, 2D and 3D, respectively; P < 0·001). Live and carcass daily growth rates per pig place decreased with increase in number of sale days (live: 772, 680, 670 g/day and carcass: 658, 575, 571 g/day; P < 0·001). Carcass gain per unit area decreased in split-marketed groups (358, 318, 312 kg/m2 per year for 1D, 2D and 3D, respectively: P < 0·05). Carcass weight variation (s.d.) within pen decreased with each increase in number of sale days (s. d. 5·28, 3·81 and 1·74, respectively; P < 0·001). In conclusion, pigmeat output, as measured by carcass gains per m2 per year, was improved with increase in group size and by marketing all pigs in a group on a single day.