Two feeding trials were carried out with Israeli Friesian male calves, commencing at an average age of 7 to 10 days, and covering a suckling period of 30 days followed by a further 90 days. A conventional starter, or one that contained cotton hulls, was used. In each experiment one group of 10 animals served as a control and a similar group was monensin-supplemented. No coccidia were found in the animals. In experiments 1 and 2 monensin supplementation was associated with increased daily gains of 10% and 47% during the suckling period and of 6% and 17% during the next 90 days, but only the differences obtained in experiment 2 were significant. In both experiments, dry-matter intake relative to body weight was higher with monensin supplementation in period 1, but reduced in period 2. The effect of monensin on molar proportions of acetic and propionic acids was smaller than that reported by previous authors for older cattle.

A separate digestibility trial showed that monensin administered to suckling calves, either with milk replacer or directly into the rumen, improved dry-matter digestibility, increased the excretion of amylase, and tended to reduce that of trypsin and chymotrypsin.

Five hundred and seven British Friesian × Ayrshire bull calves were reared on a once-daily milk replacer feeding system from approximately 6 to 72 days of age in four naturally ventilated, unheated calf houses differing in design and degree of insulation. Environment within the calf houses was monitored each hour. Differences in design and degree of insulation produced small but significant differences in internal house temperature, humidity and air movement which had no measurable effect on calf daily live-weight gains.

Calves receiving 0·6 kg/day compared with 0·3 or 0·4 kg/day of milk replacer plus concentrates ad libitum ate less concentrates but had higher daily live-weight gains (0·56 compared with 0·49 kg/day respectively) (P < 0·001). Rations supplying similar amounts of metabolizable energy from varying proportions of milk:concentrate resulted in comparable live-weight gains. Results suggest that calf viability was affected by level of nutrition and that low levels of milk replacer feeding resulted in higher mortality. Naturally ventilated, unheated calf houses were demonstrated to be suitable for rearing calves in south-west Scotland.

1. The primary growth of a tetraploid red clover was cut from 17 to 19 June and ensiled with formic acid at 3·81/t fresh crop (F), equal volumes of formic acid and formalin at 9 11/t (67 g formaldehyde per kg crude protein) (FF) or wilted and ensiled without additive (W). The silages were given ad libitum either alone or with supplements of dried grass or barley/fish meal at 6·7 g dry matter per kg live weight to 45 British Friesian male castrates, initially 3 months old and 104 kg live-weight.

2. The use of formaldehyde reduced the concentration of fermentation acids and of ammonia-nitrogen in the silage. Wilting the crop increased silage dry-matter content by 74g/kg fresh weight but this silage had the highest concentration of fermentation acids and of ammonia-nitrogen.

3. Digestibilities of diets containing silage FF were lower than those of diets containing silages F and W except when silage FF was supplemented with dried grass (interaction P <0·05).

4. The intake of silage W was on average higher than that of silages F and FF (P < 0·001). Supplements of barley/fish meal and dried grass depressed silage intake to a similar extent (P <0001). When silages were given as the sole feed, calves consuming silage F had higher live-weight gains than calves given silages FF and W (P <001). This effect was not apparent when silages were supplemented with barley/fish meal, but with a supplement of dried grass the calves given silage FF grew more slowly than those given silages F and W.

5. The results are discussed in relation to the possible effect of treatments on the supply of rumen-degradable protein and of amino acids to the animal.

1. A primary growth of perennial ryegrass was cut on 8 to 11 May (early) or on 12 June (late) for comparison with the primary growth of a tetraploid red clover, which was cut either on 1 or 2 June (early) or on 28 June (late). The crops were ensiled, after wilting for about 4h, with the addition of formic acid at 2·21/t fresh crop. The silages were given ad libitum alone or with rolled barley at 11·5 g dry matter per kg live weight to 40 British Friesian steers initially 3 months old and 108 kg live weight.

2. On average there was no significant difference in digestibility between perennial ryegrass and red clover. However, the rate of decline in digestibility with time was greater with perennial ryegrass than with red clover.

3. Calves given silage of red clover as the sole feed ate more dry matter and grew faster than calves given grass silage (P <0·001) but supplementation with barley reduced the intake of red clover silage to a greater extent than that of perennial ryegrass silage. Barley supplementation increased live-weight gain of calves given perennial ryegrass from 0·32 to 0·83 kg/day and that of calves given red clover from 0·63 to 0·99 kg/day (interaction P <0·05). The results did not indicate a higher net efficiency of utilization of the legume. Date of cut had no significant effect on dry-matter intake but earlier cutting resulted in an increase in live-weight gain from a mean of 0·61 to 0·77 kg/day (P <0·001).

4. The results show that high rates of live-weight gain (0·74 kg/day) can be achieved by calves given silage of red clover and that earlier cutting of herbage for silage does not always result in higher intakes of dry matter. Supplementation of silages with barley can reduce markedly the difference in intake and live-weight gain apparent when the silages are given as sole feeds.

The effects of 18 buffalo sires, used in 2 years of a progeny-testing programme, on the subsequent lactation performances of their mates, were investigated from a study of 685 lactation records. The traits studied were: milk production, lactation length, length of post partum anoestrus, number of services per conception and length of service period (calving to conception). Parity of calving and sire had a significant effect on 305-day milk yield and lactation length of the mates. Between the 2 years, the sires did not differ for any of the traits of their mates. Although the breeding value of the sires, high or low, did not differ significantly, the sires with high breeding value tended to depress the milk production in the subsequent lactation of their mates and vice versa (r= −0·05). The birth weight of the calves significantly affected milk production. It was concluded that all methods of sire evaluation are likely to be biased by the effect of sires.

Insulin, thyroxine and tri-iodothyronine concentrations were measured in samples of blood from 175 Friesian bulls, aged between 2 and 7 years, which were being progeny-tested for milk production. Least squares regression coefficients were estimated for these hormone levels on time of day and time after feed at sampling and age of bull. Correlations between hormone levels and Improved Contemporary Comparisons of the bull, a measure of his daughters' milk production, did not differ significantly from zero, suggesting that simple spot estimates of levels of these hormones in bulls would not supply useful predictors of daughters' production.

A study was made of the performance of different grades of Friesian × White Fulani crosses using 12 years' records from 1967 to 1978. Milk yield increased progressively with increases in the proportion of Friesian genes. Lactation length also showed a similar trend, with a difference between 1/2 and 7/8 grades of 41 days. Calving intervals averaged approximately 390 days and did not differ among grades. Calf mortality was high, varying from 16 to 29%. The optimal genetic contribution from the Friesian for this environment is considered to be higher than 75 %

A randomized block experiment was used to assess the effects of wilting of herbage prior to ensiling. Three silages, each a composite of three harvests taken over the season, were prepared by ensiling herbage as unwilted, medium-wilted or high-wilted material with mean dry-matter contents in the resulting silages of 192, 254 and 455g/kg respectively. The silages were ensiled in bunker silos using the same harvesting machinery and with formic acid applied at the rate of 2 81/t of herbage. The silages were offered to 81 January- and February-calving cows from the 8th day post partum until going to pasture on 27 April, with a mean period on treatmen t of 92 days. In addition, all animals received a fixed concentrate allowance of 7·6 kg/day. Wilting increased silage dry-matter intake, the mean intakes being 9·2, 9·4 and 10·0kg/day for the unwilted, medium-wilted and high-wilted material respectively, but resulted in a significant depression in milk yield, with the yields obtained during the final 14 days on treatment being 23·6, 21 -8 and 21·5kg/day respectively. Milk composition, live weight, body condition, total ration digestibility and nitrogen-balance data are also presented.

Most farms that were feeding complete diets to dairy cows in the east midlands lost barley to starlings during the 1978/79 winter and more outdoor than indoor feeding sites were infested. The maximum total loss recorded on any one farm was 11 -881, this being 9% of the 1321 of barley presented to the cattle. The presentation of ground barley, rather than rolled barley, reduced the quantity of grain removed by starlings but the proofing of buildings i n which cattle are fed complete diets is suggested as the most effective means of preventing this food loss.

1. Two experiments were conducted to examine the effects of a cereal-based supplement and herbage mass on the intake and performance by Border Leicester × Scottish Blackface ewes nursing twin lambs in early lactation.

2. In one experiment 16 ewes, individually penned, were given one of four amounts of supplement (0, 320, 640 and 960 g organic matter per ewe per day) and offered ad libitum freshly-cut perennial ryegrass herbage (organic-matter digestibility 82%). Intake of herbage and total organic matter digestibility declined linearly with increasing intake of supplement (0·84 g organic matter of herbage per g organic matter of supplement and 0·50 percentage units per 100 g organic matter of supplement respectively).

3. In the second experiment three amounts of supplement (0, 480 and 960 g organic matter per ewe per day) were offered individually to groups of seven ewes grazing a perennial ryegrass sward of high digestibility, maintained at herbage masses of either 500 or 750 kg organic matter per ha. A further group of seven unsupplemented ewes were grazed on the same sward maintained at 1500 kg organic matter per ha. Intakes of herbage and digestible organic matter by ewes, and lamb live-weight gain, were all significantly greater and ewe live-weight loss significantly less at herbage masses of 750 and 1500 tha n at 500 kg organic matter per ha (P <0·05). The mean decline in herbage intake was 0·93g organic matter per g organic matter supplement consumed. Amount of supplement had no significant effect on lamb live-weight gain at either weight of herbage nor on ewe live-weight loss at the 750 kg organic matter per ha herbage mass. At 500 kg organic matter per ha herbage mass, intake of digestible organic matter was significantly greater and ewe live-weight loss was significantly less for 960 than for 0 and 480 g organic matter per day amounts of supplement (P <0·05).

Two groups of 15 ewes in store body condition were either given a maintenance level of feeding or a twice-maintenance level (flushed) during the course of one oestrous cycle. Five ewes from each feeding level were slaughtered at 0, 18 or 48 h after the onset of the oestrus at the end of the treatment period and measurements were made of the luteinizing hormone content of their pituitary, the luteinizing hormone concentration in their blood plasma, their ovulation rates, and ovarian follicle numbers and sizes.

‘Flushed’ ewes had a significantly higher ovulation rate (260, s.e. 0·24 v. 1·80, s.e. 0·20; P <0·05), although there was no significant difference in either pituitary luteinizing hormone content or plasma luteinizing hormone concentrations at oestrus.

Analysis of the patterns of ovarian follicle distribution suggest that flushing ewes for one oestrous cycle might increase ovulation rate by preventing the late atresia of large follicles in the last 30 h before ovulation.

Twenty-four pigs were weaned at 21 days of age and given restricted feed allowances for the subsequent 8 days. Eight suckled pigs served as control and gained 320 g daily, of which approximately 40 g were lipid and 40 g protein. Pigs were slaughtered at 2-day intervals, physically dissected into non-carcass, carcass fatty tissue and carcass muscle plus bone, and these fractions were then analysed for water, protein and lipid. On average, weaned pigs made small positive body-weight gains. In comparison with suckled pigs, weaned pigs contained more water and less lipid but the same protein, and more non-carcass and less carcass fatty tissue but similar carcass muscle plus bone. Losses of lipid were offset by gains of water and associated with an increase in the percentage water content of carcass fatty tissue. At zero weight gain, pigs lost 43 g carcass fatty tissue, gained 37 g non-carcass, lost 56 g lipid and gained 53 g water, while carcass muscle plus bon e and protein gains were themselves not significantly different from zero. No change in carcass fatty tissue weight was associated with counterbalancing losses of lipid (18 g) and gains of water (15 g) and protein (3g). Lipid catabolism to support anabolism of essential body tissues commenced in the weaned pigs when weight gains fell below 193 g/day; this was about two-thirds of the gains achieved by the suckled control pigs. Plasma free fatty acid concentrations indicated that maximum lipid catabolism to occur on the 2nd day after weaning, and to reduce thereafter as body fat stores were progressively depleted.

Twenty-four Large White × (Landrace × Large White) gilts were allocated to one of four treatments such that one gilt from each of the litters was on each treatment. Three of the treatments involved 30-min daily contact with a boar, the boar being either (1) 2 years of age, (2) 11 months of age, or (3) 6·5 months of age, at the start of the trial. The fourth group were controls, receiving no boar stimulation.

The experiment began at a gilt age of 165 days and continued until puberty was detected. The gilts were slaughtered 5 days after puberty was reached.

The results indicate no significant difference for age at puberty between gilts exposed to the 2-year- or 11-month-old boars (182·0 v. 181·6 days respectively), although both were significantly younger at puberty than gilts exposed to the 6·5-month-old boars or having no boar contact (P<001) (206·0 v. 203·0 days respectively).

To assess the variability of hormone values obtained from calves at an early age, plasma concentrations of prolactin, growth hormone, insulin and thyroxine were measured in blood samples taken twice-weekly from seven heifers maintained under commercial conditions during their first 110 days of life. With the possible exception of thyroxine, there was considerable variation in the concentration of each hormone in each animal throughout the period of sampling, thus indicating that twice-weekly sampling was inadequate for investigating differences in hormonal concentrations between cattle of different production potential. Although there were trends in the pattern of plasma hormone concentrations as the calves progressed from the pre-ruminant to ruminant states, few of the changes during the pre-weaning, weaning and post-weaning periods were consistent between animals.

Five groups of six Hereford × Friesian steers, approximately 1 year old and weighing 363 kg at implantation, were individually fed according to body weight and slaughtered 100 days after implantation. Group 1 was sham-implanted subcutaneously in the ear. Group 2 was implanted with 20 mg of the steroid oestradiol-17β group 3 with 140mg of the steroid trenbolone acetate; group 4 with oestradiol-17β in one ear and trenbolone acetate in the other; and group 5 with oestradiol-17β and trenbolone acetate as a single implant in one ear.

Groups 1 to 5 had mean overall live-weight gains (±s.e.) of 0·79, 0·88, 0·89, 0·98 and 1 15±0·067kg/day; mean feed conversion ratios of 9·30, 8·78, 8·45, 8·13 and 6·92 + 0·61; and mean cold carcass weights of 236, 246, 250, 252 and 257 ± 6.4kg, respectively. Oestradiol-17/? reduced omental (P <0·05) and kidney (P <001) fat. The two steroids appeared to produce independent and additive effects except when used together as a single combined implant (group 5), when the effect on live-weight gain was more prolonged. The mean concentrations of oestradiol-17/i in plasma in groups 2, 4 and 5 were greater than in the control group at 28, 28 and 91 days after implantation respectively (P < 0·001). Trenbolone acetate was present in the plasma in groups 3, 4 and 5 throughout the experimental period.

Field data were analysed in an attempt to identify factors contributing to differences between haemoglobin types n i the proportion of ewes lambing per ewe exposed to the ram in flocks grazing oestrogenic pastures. The number of ewes mated and the proportion of ewes failing to conceive to first service per ewe exposed to the ram were analysed. Neither was found to significantly differ between matings of different haemoglobin type. It is concluded that differences in reproductive performance between haemoglobin types could possibly result from differences in embryo survival.

The rate of heat transfer from a model animal, covered with one of three animal pelts, was measured when the pelts were dry and when they were exposed to a fine spray of water. Wetting of the pelts increased heat transfer by 192, 114 and 15W/m2 respectively for the hairless skin, the skin with calf's hair coat (5 to 10 mm) and the skin with the lamb's fleece (60 mm). These results demonstrate the considerable protection against the thermal effects of wetting which is provided by animal coats, particularly if these are relatively deep.

The elements of prolificacy have been analysed for the D'man sheep, a prolific Moroccan breed, by laparotomy on 38 animals. The average ovulation rate was 2·50 (s.e.0·45); a slight difference was observed between nulliparous and multiparous ewes due to high simultaneous activity by both ovaries in the latter group. Embryonic survival (42% overall) was 94% (87 to 100%) for multiparous and 44% (36 to 52%) for the nulliparous ewes at one ovulation, decreasing with increasing numbers of corpora lutea. The average litter size showed an optimum at four ovulations.

Whole, moist barley treated with ammonia (A), whole, untreated barley (WU) and ground barley (G) were fed with hay and a little high protein, mixed concentrate. Digestibilities of dry matter, organic matter and crude fibre, assessed with young adult female sheep, were highest in diet A and lowest in diet G. The digestibilities of dry matter and crude fibre were also higher in diet WU than in diet G. Digestibility coefficients for dry matter and organic matter in barley, calculated by difference, appeared higher in A and in WU than in G. Young female sheep fed on the above diets from the age of 7 to 11 months ate more hay and gained more weight on A than on G; again diet WU was intermediate. Differences also occurred between the three groups as regards volatile fatty acids in the rumen fluid. Sheep on A or WU had a higher pH in the rumen fluid than those on G. Finally, sheep on A gave birth to more offspring than those on WU or G. All these differences were significant.

ANIMAL PRODUCTION, Volume 31, Part 2, pp. 191-199

PIG COURTSHIP BEHAVIOUR: PHEROMONAL PROPERTY OF ANDROSTENE STEROIDS IN MALE SUBMAXILLARY SECRETION

G. C. Perry, R. L. S. Patterson, H. J. H. MacFie AND C. G. Stinson

On page 193, Fig. 2, the legends on the figure have been reversed:

upper legend should read 'Gilt receptive to boar';

lower legend should read 'Gilt non-receptive to boar