The influences of age at first pregnancy and number of suckling young on maternal performance of mice were studied. Mean mating ages for early-pregnant and normal-pregnant females were 27 and 52 days respectively. Litter size from parturition (day 0) to day 12 of lactation was standardized to either 8 or 12 pups. The more rapid (P<0·01) growth rate and feed conversion efficiency of early-pregnant dams from mating to parturition continued from 0 to 12 days of lactation but occurred primarily in the first 3 days of lactation, so that there were no differences in body weight or feed intake from days 3 to 12 of lactation. There were no age at pregnancy effects on total mammary gland DNA, RNA or RNA/DNA ratio at day 12 of lactation or on individual progeny weights or feed conversion efficiency of litter growth from 3 to 12 days of lactation. Dams suckling eight young had a lower (P<0·01) feed intake, gain and feed conversion efficiency from 0 to 3 days of lactation. From 0 to 12 days of lactation, these dams were smaller, consumed less feed and their individual progeny weights were larger (P<0·01). Dams suckling eight pups had smaller (P<O01) mammary glands, less (P < 0·05) mammary gland DNA and a higher (P<0·05) RNA/DNA ratio. Interactions between pregnancy age and number suckling were not significant. Feed intake of the dam from 0 to 12 days of lactation was influenced more by litter weight gain (34%) than either dam weight gain (5%) or metabolic body size (6%). Maternal performance of mice, based on pup growth and mammary gland growth and function, was not affected by early pregnancy.

Experiments were conducted to observe the taste responses of male and female calves to various levels of sodium salts, chloride solutions, and trace minerals. Animals were penned individually and given a completely pelleted ration ad libitum. Trace mineralized salt was freely available.

Using water as a basis for determination, a non-discrimination zone was established. This zone represented an intake ranging from 63 to 37%. Preference threshold was set at 80% of intake, while the rejection threshold was set at 20% of intake. Responses were determined by expressing the intake of the test solution as a percentage of the total intake during the test period. Responses at a given chemical concentration were measured during two 8-hr periods.

Taste response observations were made on the following: 0·02, 0·08, 0·32 or 1·25% sodium chloride (NaCl), sodium sulphate (Na2SO4), sodium bicarbonate (NaHCO3), sodium carbonate, monobasic sodium phosphate (NaH2PO4), dibasic sodium phosphate (Na2HPO4), ammonium chloride, potassium chloride, calcium chloride, magnesium chloride, and manganese chloride. In addition, observations were made when 0·02, 0·08, 0·32 or 1·25% NaHCO3, Na2SO4, or Na2HPO4 were offered in opposition to equal concentrations of NaCl. The responses to 5, 10, 20, 40 and 60 p.p.m. concentrations of cupric chloride, zinc chloride, molybdenum trioxide and cobaltous chloride were observed also.

Two milk replacers identical in composition except for the protein source, which was either fish-protein hydrolysate (FPH) or dried skim milk, were offered either twice or four times daily to castrated British Friesian male calves in four ratios: 100 FPH 0 Milk; 67 FPH 33 Milk; 33 FPH 67 Milk and 0 FPH 100 Milk. Concentrates and hay were offered ad libitum, and the calves were weaned at 42 days of age. Feed intake and calf live weight were recorded to 100 days of age.

There were no differences in growth rate up to weaning due to frequency of feeding. Up to 67% FPH there were no differences in growth rate but calves on the 100% FPH diet showed a 40% depression in growth compared with the other three levels. Up to 100 days there was no apparent effect of treatment on live-weight gain, but only differences of 12 to 13% would be significant.

The results indicate that at least two-thirds of the milk protein could be replaced by FPH. The need for further work using dried material and FPH from other species is discussed.

Two fibrous roughages, wheat straw and cotton hulls, were treated with 0, 40 and 80 g sodium hydroxide (NaOH)/kg roughage, applied in amounts of water calculated to bring the roughages to moisture contents of 30 and 60%. The effects of these factors on the nutritive values of the two roughages were examined using a 2 × 3 × 2 factorial design.

Digestibility trials, in vitro and in vivo, and a 9-mo feeding trial were carried out with the roughages soon after treatment. Concentrates were limited to 6 kg/head per day throughout the animal experiments and roughages were offered ad libitum.

Neutral detergent fibre decreased by 7·8 and 13·5% with the 40 and 80 g application rates of NaOH respectively.

The treatment of both roughages with NaOH increased considerably their in vitro dry matter digestibility and total solubles after enzyme treatment, the increases being related to the rate of application of NaOH. Digestibility in vivo was improved only by the 40 g NaOH treatment.

Treatment with NaOH reduced the voluntary intake of both roughages. Only the 80 g/kg treatment had a positive effect on rate of live- and carcass-weight gain. On the other hand, NaOH improved very significantly the efficiency of conversion of metabolizable energy into live and carcass weight and increased significantly the degree of fatness of the animals. These results indicate a marked improvement in the nutritional value of both roughages due to NaOH treatment. The reason for the small response in rate of gain may be explained by a shortage of protein owing to a possible reduction in its digestibility. Cotton hulls excelled wheat straw in almost every respect. Animals on NaOH-treated cotton hulls bloated chronically unless some long straw was given. Moisture level had practically no effect on performance.

The effects of the treatments on rumen or blood constituents were small.

Pre-weaning growth data from 3822 calves reared in 11 Victorian herds were analysed. The results suggested that the superiority of males (bulls) over castrated males (steers) in pre-weaning growth was due, at least partly, to the early castration of poorly growing male calves, i.e. to the effects of early selection. The extent of this selection bias was further examined using results from similar studies and from experiments in which bulls and steers were selected without bias. These studies strongly supported the view that the superiority of bulls over steers was primarily due to selection and not to sex effects. If sex did influence the bull-steer difference it was of no statistical or practical importance.

In the Victorian data, the ratio of bulls to steers was higher in subclasses in which average growth rates were higher. When selection effects are correlated in this way with other environmental effects such as age of dam effects further biases may arise in estimation of those effects and hence in individual or mass selection.

The results indicated, therefore, that unless bulls and steers are treated as one sex biases can arise in both individual selection and progeny selection.

Using pre-weaning records of 3822 calves from 11 Victorian herds, mean male and female growth rates and corresponding sex differences were calculated for each dam age and herd-year class. From these means simple regression equations relating sex differences and growth rates were calculated. There was a close similarity between equations based on dam age means and those based on herd-year means while correlations between sex differences and male growth rates were high.

These results showed that sex differences and female growth rates could be predicted reliably from the level of environment as measured by male growth rate. Sex differences predicted by these regression relationships differed markedly from those predicted by the simple multiplicative and simple additive models generally used in adjusting for sex differences in selection.

The results also suggested that other differences such as breed differences may be predictable in the same way and that such differences are determined primarily by the level of environment per se rather than differences in the nature of the components contributing to that level.

1. Wilted (32% dry matter) Italian ryegrass was conserved: (A) untreated; (B) with 16·3 g/kg dry matter (4·6 1/t of fresh material) of an 85% w/w formic acid additive; (C) 12·1 g/kg dry matter (2·3 1/t fresh material) each of 85% formic acid additive and formalin (40% w/v formaldehyde); (D) 5·8 g/kg dry matter (1·3 1/t fresh material) each of 85% formic acid additive, formalin and a 96% w/v solution of propionic acid. The silages were individually fed ad libitum to 40 15-mo-old British Friesian steers of about 350 kg initial live weight.

2. Treatment with additives inhibited fermentation, resulting in silages with higher levels of water soluble carbohydrates and lower levels of organic acids than untreated material. Lower levels of ammonia N and higher levels of true protein indicated that some protein protection resulted from the formaldehyde treatment.

3. Formic acid alone (B) had little effect on digestibility but significantly (P<0·05) enhanced dry-matter intake, live-weight gain and nitrogen retention relative to the control (A)

4. Whereas the application of formaldehyde (Treatments C and D reduced the digestability in vivo of nitrogen, significant increases in nitrogen retention were recorde relative to the control (A). Dry matter intake was not affected significantly by treatment with formaldehyde, but at the higher level of application (Treatment C) daily gain was significantly reduced compared with the control (A). These effects are discussed in relation to possible changes in VFA patterns within the rumen and to the levels of formaldehyde used.

Dried grass pellets of high density (1·3 g/ml) were fed ad libitum to British Friesian male calves 5 to 7 mo old (Experiment 1) or 2 to 5 mo old (Experiment 2). All eight animals in Experiment 1 and eight out of 12 in Experiment 2 were fitted with rumen fistulae. In some subperiods of both experiments, pellets were broken down in water and administered as a slurry directly into the rumen at a level equivalent to approximately one-third that of voluntary intake. Intake per os was significantly reduced by this treatment but total intake (per os+per rumen) was not affected.

In Experiment 3 pellets of high (1·24 g/ml) or medium (1·14 g/ml) density were fed ad libitum to 40 9-mo-old Suffolk × Scottish Halfbred wether sheep, either alone or with access limited to 3 hr a day, in which case chopped hay was always available. Pellet density did not affect total intake, but when offered as supplements to hay the consumption of medium-density pellets was higher than that of high-density pellets. In all three experiments animals required 2 or 3 weeks to reach maximum intake of pellets. Over the 42 days of Experiment 3 the proportion of pellets in the feed consumed by animals given pellets as supplements to hay increased from 60 to 80%.

The nutritive value of four silages was compared using eight rumenfistulated wethers. Wilted ryegrass was ensiled without additive (A); with formic acid (13·9 kg/t dry matter) (B); with formic acid (10·3 kg/t dry matter) plus formalin (formaldehyde at 4·8 kg/t dry matter) (C); with formic acid (4·9 kg/t dry matter) plus formalin (formaldehyde at 2·3 kg/t dry matter) plus propionic acid (5·6 kg/t dry matter) (D).

Dry-matter intakes were 13·8, 15·1, 14·3 and 14·3 g/kg live weight for A, B, C and D respectively. Digestibilities of organic matter and dry matter were not affected by the additives. Digestibility of nitrogen and peak ruminal ammonia concentration were significantly (P<0·05) reduced by the addition of formaldehyde.

The effect on rumen fermentation characteristics, of chemically restricting in-silo fermentation, is illustrated. Differences in the rumen volatile fatty acids and in the efficiency of utilization of the energy for growth, fattening and lactation are discussed.

Data from 14 074 gilts, performance-tested on 66 farms, were matched with those from 3835 station-tested boar sibs, the whole comprising progeny test results on 456 sires. Both groups of data were adjusted independently for effect of month of test and the farm data further adjusted to a constant weight of 91 kg. Analysis of variance and covariance was carried out within herds using weighted sire progeny means. Phenotypic correlations between the same traits recorded ‘on-farm’ and in station, ranged from 0·12* (weight/age) to 0·25** (‘C’ + ‘K’ fat depth) while genetic correlations, computed using the estimated accuracy of each test, ranged from 0·23* (weight/age) to 0·49** (simple performance test index). Correlations were generally higher in Large White than in Landrace pigs.

1. Two experiments were conducted, one with pigs fed individually on a restricted scale of feeding, and one with pigs fed ad libitum in groups, to test Probioticum as a feed additive with and without nitrovin and zinc bacitracin.

2. Growth rate, feed conversion, killing-out percentage and carcass quality were measured.

3. No significant difference was shown in any of the characteristics measured between diets containing any of the additives, singly or in combination.

Body weights were recorded at birth, 45 and 90 days on 199 Merino lambs. Serum samples were obtained and analysed with horizontal starch gel electrophoresis to identify the transferrin types. Sixteen transferrin phenotypes, TfAA, TfAB, TfAM, TfAD, TfAE, TfBB, TfBM, TfBD, TfBE, TfMM, TfMD, TfMS, TfME, TfDD, TfDE and TfEE were detected in this study. The phenotypes were confirmed on the basis of international nomenclatures. Lambs were grouped according to their transferrin types. The average weight of different groups at birth and the weight gains in the first and second 45-day periods were estimated. TfDE was the poorest weight gainer but the differential value was significant only in the second 45-day period.

The in vitro dry-matter digestibilities (IVDMD) of three rations containing different proportions of hay and a mixed concentrate (pellets) were each determined by fermenting the feeds with inocula obtained from rumen contents of sheep fed on either the hay, hay and pellets, or pellets. These inocula had no significant effect on the IVDMD which averaged 60·9, 68·8 and 77·8% for the hay, hay and pellets, and pellets respectively.

Measurements were made of the heat production of cattle while standing at rest or walking on a treadmill at different speeds, both on the level and at a gradient of 6°. The energy cost of horizontal locomotion was about 2 J/kg per m at speeds of 40 to 85 m/min, irrespective of body weight or plane of nutrition. The energy cost of vertical locomotion was about 26 J/kg per vertical m.

Animal Production, Volume 22, part 2, pp. 217–223

Beef production from formic acid-treated and wilted silages

C. E. Hinks, I. E. Edwards and A. R. Henderson

Page 218, lines 7 and 11: formic acid was applied at 3·6 and 6·3 kg/t of fresh material, and not at 36 and 63 g/t.

Table 2: intakes are expressed as W0·73, and not W0·75 as indicated.

Animal Production, Volume 24, part 1, pp. 125–162

Titles and Abstracts of Papers for Presentation at the 66th Meeting of the British Society of Animal Production, Harrogate, 21 to 24 March 1977

Page 150, abstract 60: the third author is R. Thompson, ARC Unit of Statistics, Edinburgh.

Page 157, abstract 74: the sentence beginning on line 11 should read ‘The response to supplementary feeding was variable but 1·6 kg concentrates were required for every extra kg milk.’