Twenty-four Friesian steers, initially 5 months of age, were involved in a 2 × 2 factorial experiment which spanned grazing and silage feeding periods of 22 weeks' duration. In the first period, cattle were stocked at a uniformly high density, with half of the group being fed 1·25 kg/head per day of supplementary barley. In the second period, the cattle were subdivided into four groups and fed varying levels of barley with silage. Finally all the animals received 3·65 kg/head per day of barley. Replicates of the four treatments were slaughtered at random after 5 to 11 weeks on this treatment. Whilst supplementary cereal feeding significantly increased the live-weight gains of steers at grass by 11%, this live-weight advantage was offset by their slower gains in the final weeks before slaughter. Feeding cereals to grazing cattle had little effect on carcass composition or the proportions of carcass joints, but their beef was considered, by a tasting panel, to be more tender than the meat from the control steers.

Increasing the level of barley fed with silage only increased live-weight gains by 2%, and had little effect on carcass or meat quality.

A numerical model of male and female replacement processes is developed and used to construct a matrix which specifies the numbers of lactations of different parities expressed in a given time period by daughters of bulls used in artificial insemination (AI).

Populations resulting from newly established AI breeding programmes contain an unduly high proportion of offspring by young bulls. Subsequently an equilibrium is reached in which offspring of young and tested bulls are present in proportions determined by the relative usage of the two types of sire and by differences in replacement rates amongst their progeny. Once an equilibrium has been reached the numbers of progeny sired by bulls lacking a progeny test proof is extremely small.

The use of the technique to solve a number of specific planning problems is demonstrated.

1. The growth, feed consumption per unit weight gain, carcass characteristics and some aspects of meat quality were studied in two trials with crosses derived from Landrace (L), Pietrain (P), Hampshire (H) and Large White (LW) breeds.

2. In Trial 1, 96 pigs of both pure Landrace and LW(× (L♀ × P♂)♂ origin were studied up to slaughter weights of 64 and 91 kg live weight. In Trial 2, Landrace, LW♀ × (L♀ × P♂)♂ and LW ♂x (P♀x L♂)♂, (H♀ × P♂ × L♂ and (H♀ × P♂)♀ × LW♂ pigs were compared up to 91 kg live weight using 48 pigs of each type.

3. All crossbred types showed better economy of production than Landrace when assessed by live-weight gain and feed consumption per unit weight gain. Their carcasses contained greater quantities of lean meat and similar quantities of rind, bone and fat than Landrace at comparable weights, but they exhibited a variable tendency to poorer meat quality. LW × (L × P) and LW × (P × L) carcasses at 91 kg live weight were shorter than Landrace; 4% and 14% of pigs in trials 1 and 2 respectively were less than the currently acceptable length of bacon pigs (775 mm). (H × P) × LW and (H×P)×L carcasses at this weight were much shorter; 34% and 38% respectively were less than 775 mm.

Groups of individually-fed pigs, each of three gilts and three castrates of mean live weights 18, 31, 46, 58, 72 and 80 kg, were given for 20 days feed allowances based on the ARC estimates of energy required for maintenance, assuming an efficiency of utilization of digestible energy (DE) of 77% for maintenance. As the actual diet used had a higher DE value than that calculated before the start of the experiment, DE intakes (260·3 W056) were about 4·0% above the ARC values.

There was no statistically significant change in live weight over the period of study. This supports the validity of the ARC estimates, if maintenance is defined as a lack of change in body weight.

The metabolizable energy (ME) intakes (248·3 W0·56) which maintained weight were also close to other estimates of ME requirements.

Two experiments concerning the effects, on the carcass and meat characteristics of 18-months-old Friesian steers, of variation in grazing intensity and the level of barley feeding with silage are reported.

Groups of 12 steers were grazed at different intensities over 5-month grazing periods, such that live-weight differences of 38 kg and 16 kg were recorded at housing. No compensatory growth was recorded during the subsequent winter feeding period.

Whilst the grazing treatments had little effect on carcass or meat quality, higher levels of barley feeding with silage over the winter period (710 v. 410 kg/steer) had significant effects on live-weight gain, and increased carcass weight by 21 kg at slaughter. The higher yield of carcass weight was reflected in significant differences in carcass composition, joint proportions and retail cut-out value. Sixty per cent of the carcass weight difference was removed as trim fat. Differences in carcass fatness were not associated with any differences in eating quality.

Six Hereford and Shorthorn cross steers were ultrasonically scanned in parallel planes perpendicular to the spine. Scanning was performed at the level of each vertebra and extended from the head of the 9th rib to the articulation of the 3rd and 4th lumbar vertebrae. Scans of each live animal were compared with those of its hot carcass and related to dissected sections of the frozen carcass. In general, the difference between an ultrasonic estimate and the carcass measurement was found to depend on the anatomical parameter being investigated, the location on the animal at which measurement was made and the individual interpreting the scan. Results are presented for fat thickness, Mm. longissimi thoracis et lumborum depth, ‘A’, ‘B’ and area measurements. Possible explanations for some discrepancies between the ultrasonic and carcass measurements are discussed.

Additional results showed that whilst judges are consistent within themselves, in general their interpretations of ultrasonic scans differ significantly from each other.

Thirty-six weaner pigs of average initial live weight of 16 kg, and of Large White and Landrace breeds, were allocated to six treatments differing in the level of zinc supplementation (from 0 to 500 p.p.m.) of a basal diet containing approximately 24% crude protein on a dry-matter basis. At the final live weight of about 50 kg, four pigs from each treatment were slaughtered and the hair, skin, lung, heart, kidney, pancreas, liver and spleen were sampled and frozen until they were analyzed for their zinc contents. Appetite and weight gain tended to be reduced at high levels of zinc supplementation (200 to 500 p.p.m.) though not significantly so. The average total zinc consumed per pig increased with increasing levels of zinc supplementation, but organ weights were not consistently affected by the levels of zinc in the diets. Only for the hair, skin, spleen and the kidneys was any significant variation in zinc concentration found among the treatment groups, but there were no consistent trends related to the level of dietary intake of Zn. Hair had the highest zinc concentration per kg of tissue, followed by the liver, pancreas, spleen, kidneys, heart, the lungs and the skin, in that order. The organs showed very little or no increase in the Zn concentration, in the Zn-supplemented groups compared with the unsupplemented, except that the liver showed slight increases up to a level of supplementation of 300 p.p.m. followed, however, by a decline in concentration at higher dietary levels of Zn.

Allowances of about 1·4M, 1·8M, 2·2M, 2·6M, 3·OM, and 3·4M (M = feed required for maintenance) were compared for pigs growing over the live-weight ranges 20·40, 40·60, 60·80, and 80·100 kg, with feed conversion efficiency (FCE) as the main response criterion.

Response to increased digestible energy (DE) allowance was curvilinear; FCE improved rapidly up to 2·2M-2·6M, and changed much less with intakes above 2·6M. It is concluded that optimum FCE occurs at about 2·7M for pigs of 30 kg and at about 3·OM for pigs of 50, 70 and 90 kg.

Allowances of dietary DE suggested by the Agricultural Research Council correspond to 2·56M, 2·95M, 3·04M and 3·08M for pigs of 30, 50, 70 and 90 kg live weight, respectively. It appears that these are near to the optima in promoting the best FCE.

Changes of −25%, −15%, −5%, +5% and +15% in daily intake around the optimum levels caused FCE to deteriorate by averages of about 13%, 4·5%, <1%, <1% and 4·5% respectively. Daily weight gains would then change by about −34%, −18%, −5%, +4% and +10%, respectively.

Length and diameter of teats were measured on first-lactation cows at Danish progeny testing stations. The cows were also classified into four groups according to shape of teat and teat tip. All traits were corrected for yield level and interval after calving and correlated with milking characteristics. The conclusions drawn were:

1. Teat length influences both average rate of milk flow and yield on hand stripping. The most satisfactory milking is obtained in cows with short teats. In Red Danish, Black and White Danish and Jersey cows, respectively, desirable length of fore teat is ≤ 6, ≤ 6, and ≤ 5 cm, and of rear teat about 1 cm shorter.

2. Teat diameter is of no significant importance to average rate of milk flow, but yield on hand stripping is most satisfactory when the diameter is ≤ 2·4 cm.

3. Teat shape must be very extreme before an adverse influence is recorded on average rate of milk flow and yield on hand stripping.

4. The milking characteristics of cows are correlated with shape of the teat tip. The highest rate of milk flow and the lowest yield on hand stripping is found in cows with flat and concave teat tips.

5. A relationship exists between teat length and the shape of the teat tip, and partial correlation coefficients show that of the teat traits investigated the most important factor affecting average rate of milk flow is the shape of the teat tip whilst teat length—similar to the effect of teat diameter—is of greater importance to the yield on hand stripping. Investigations into the possible consequences for udder health must, however, be conducted before selection for a special shape of the teat tips is introduced.

1. Four groups of 20 ewes were individually fed in late pregnancy on: (1) silage ad libitum, (2) silage ad libitum and 12 kg rolled barley, (3) silage ad libitum and 23 kg rolled barley, (4) pelleted milled dried grass ad libitum. The concentrate was offered on a rising plane over the last 6 weeks of pregnancy. After parturition the ewes and lambs were put on spring pasture.

2. The intake of silage by twin-bearing ewes fell slightly but nonsignificantly during week 16 of pregnancy but thereafter remained steady up to lambing. There was no other decline in intake on any of the treatments. Barley, however, significantly depressed silage intake when the quantity was increased above 282 g per day.

3. Single-bearing ewes, except those on treatment 1, gained in net body weight during late pregnancy. Twin-bearing ewes on treatment 4 gained in net body weight while those on the other treatments lost weight.

4. Birth weights of single lambs from ewes on treatment 1 were significantly lower than those from treatment 3. This was the only significant difference in birth weight or subsequent growth rates of single lambs. Birth weights of twin lambs on treatment 1 were significantly lower than those on the other treatments.

5. The birth weight of twin lambs appeared to be an important determinant of subsequent performance, and may thus be a valuable criterion of the adequacy of the ewe's diet in late pregnancy.

6. With medium-quality autumn silages, 12 kg of barley given during late pregnancy is sufficient to ensure good reproductive performance in ewes.

Three diets were given separately, each at four levels of digestible energy (DE) intake, to gilts, castrates and boars growing from 21 to 92 kg live weight. The energy levels were those suggested by the Agricultural Research Council, compared with a 5% increase or 10% or 20% decreases in daily allowance. One diet (ME 18) had 3·0 Meal DE/kg and 18·2% crude protein; the other two (HE 16 and HE 19) had 3·26 Meal DE/kg and 16·1% or 19·3% crude protein.

They were given unchanged throughout the experiment. Responses to change in daily DE intake were not affected by sex or diet, except in shoulder fat thickness. Feed eaten per kg gain did not vary by more than 4% over the intake levels investigated, and no difference was significant. On average, each reduction in daily intake below the ARC+5% allowance led to an increase of 1·2 percentage units of carcass lean and a decrease of 1·3 percentage units of carcass fat.

In comparison with HE 16, the higher protein diet HE 19 gave improved feed conversion efficiency and growth rate, particularly in gilts. It did not cause significant changes in carcass measurements. In comparison with ME 18, HE 19 gave more efficient conversion of DE to weight gain, and faster growth.

Boars required less feed per kg gain and had faster growth rates and leaner carcasses than gilts, which were superior to castrates. There was a high incidence of unpleasant odour in fat from boars, but some was also detected in that from gilts and castrates.

Following weaning of their first litter at 42 days post partum, 36 Landrace × (Landrace × Large White) sows were fasted for 24 hr then allocated to one of three feed levels, 1·8, 2·7 and 3·6 kg food/day, until the day after mating. During pregnancy all the sows received 1·8 kg food/day.

The incidence of infertility and anoestrus was greatest for sows fed 1·8 kg/day and least for sows fed 3·6 kg·day. Sows fed 1·8 kg/day took significantly (P < 0·01) longer (21·6 + 3·0 days) to return to oestrus than sows fed 3·6 kg/day (9·2 ± 2·2 days). The mean litter size for sows fed 1·8, 2·7 and 3·6 kg food/day was 9·4 ± 0·9, 10·1 ± 0·8 and 11·5 ± 0·6 piglets respectively, but these differences were not significant.

Seven daily doses of 60 or 120 mg cortisol administered to mature sheep given a maintenance ration depressed wool fibre diameter by approximately 10%. Similar treatment with 120 mg cortisol for 14 days produced a more severe and prolonged effect, though fibre diameter was unaffected by a series of seven injections of 40 IU ACTH given every second day.

Fourteen days at 10% of maintenance and 14 days' cortisol treatment were applied to mature sheep fed either continually at 150% maintenance, or at 75% followed by 150% maintenance. Cortisol treatment was associated with a significant reduction in fibre diameter only in the animals fed at 150% maintenance. Restriction to 10% maintenance for 14 days had no such effect. Approximately 20% of fibres were shed following cortisol treatment in both nutritional groups, but a marked ‘break’ in the fleece occurred only in the 75% maintenance group.

A low plane of nutrition is confirmed as a major factor predisposing to ‘tenderness’ and ‘break’, and short-term adrenocortical stimulation is shown to be sufficient to produce the reduction in fibre diameter and increased fibre shedding associated with these faults. However, semi-starvation (represented by restriction to 10% of maintenance) appears to have played a relatively minor role in their development.

The transport of protein across the small intestine of the newborn pig was measured in vitro. The transport of both bovine immune globulin and bovine plasma albumin showed a large variation between piglets. The polycations poly-ornithine, poly-arginine and poly-lysine stimulated both the transport of globulin and albumin. Protamine, histone and arginine were without effect on protein transport. Poly-ornithine became bound to albumin and to the piglet intestinal mucosa. The amount of poly-ornithine needed to stimulate albumin transport was of the same order as that needed to change the electrophoretic mobility of brush border membranes and some 30 times less than that needed to change the charge on the protein. It is concluded that polycations stimulate protein transport by a direct action on the brush border membrane of the pig intestinal mucosa.

The availability of Ca and P in the young growing pig was determined by the use of a radioisotopic technique. Eighteen Large White barrows of 25 kg mean body weight were used in the study, 10 being fed 1·20 kg per day of a cereal-based diet and the remainder half of this amount. At the higher dietary level the intake of Ca was 9·4 g/day, and that of P was 9·7 g/day. The mean availabilities of Ca and P were 41·5% and 78·1% respectively. At the lower level of intake there was no significant change in the availability of either element, mean values being 39·6% for Ca and 82·5% for P. These values contrast markedly with the 67% for Ca and 50% for P currently used in the calculation of dietary requirements for the elements by the factorial approach.

Twelve sows (F) were fed 7·3 kg/day and twelve (T) 3·7 kg/day of a 16% crude protein (CP) diet for the last 5 weeks of an 8-week lactation, so that at the subsequent service F sows were heavier (16%) and in better condition.

From service to slaughter 70 days later, sows received either 3·7 kg/day (H) or 1·8 kg/day (L) of a 15% CP diet, giving four treatment combinations; FH, FL, TH and TL.

In pregnancy H sows gained more weight than L sows and, on the low plane, F sows gained more weight than T sows. Ovulation rate as measured by corpora lutea count at slaughter was higher for TH than TL sows and for FL sows than FH sows. A combination of low ovulation rate and high mortality rate gave fewer foetuses (10·0) in the TL sows than in sows on the other treatments (13·5). Similarly mean foetal weight and thus foetal litter weight was least in TL sows. Foetal membranes, uterine fluids and uterine wall were lighter at slaughter in T sows than F sows and lighter in L sows than H sows, those of TL sows being appreciably the lightest.

The results indicate that when the sow is in poor condition at service, body reserves being depleted, the uterus and its contents become more vulnerable to adverse pregnancy nutrition.

A total of 523 lambing records were used to study general combining ability (g.c.a.), maternal ability and specific combining ability (s.c.a.) for three breeds of sheep, the native Ossimi and Barki and the Fleisch Merino. All possible combinations along with the pure breeds were represented. Traits studied were: birth, weaning (4-months) and yearling body weights; lamb survival at weaning; fleece weight and staple length.

Ossimi showed the highest g.c.a. estimates for all traits except birth weight and fleece weight where Merino was the best, and survival where Barki was the best. Barki showed the worst g.c.a. in all traits except survival and staple length for which Merino had the lowest estimates.

Barki exhibited the best maternal ability in weaning and yearling body weights and lamb survival, while Ossimi was best in the other traits. Merino was consistently worst in maternal ability. The two native breeds interacted more favourably with each other than with Merino in lamb production traits. Among the purebred lambs, the Ossimis performed the best in all traits except fleece weight where they were excelled by the Merinos. It was concluded that for marketing weights (i.e. weaning and yearling) and especially when viewed with respect to survival, the Ossimi × Barki cross offers the highest production; while for fleece weight the Merino × Ossimi is the best.

Sows housed with free access to water were found to have urine protein levels comparable to those recorded for man, dog and sheep. However, in stalled sows with restricted access to water, urine protein levels were twice as high as those of penned sows.

Physiological proteinuria has been found to occur in the piglet, in which respect it is similar to the ruminant and the dog. Proteinuria reaches a peak within 20 hr of birth and lasts for approximately 48 hr. The rapid decline in urine protein levels after this period coincides with gut closure. Proteinuria did not occur in piglets fed on glucose saline, only in those receiving colostrum; however, the continued feeding of colostrum did not prolong the period of proteinuria. In piglets fed varying levels of colostral protein there was a direct correlation between serum protein levels and mean urinary protein concentration during the period of proteinuria, but there was no direct correlation between the amounts of colostral protein ingested and the serum protein level.

The performance of Israeli-Friesian male calves on six rations, including two levels (15% and 30%) of ground wheat straw and oatvetch hay in pelleted mixtures, and the same two levels of ground straw in non-pelleted mixtures, was examined.

Daily live-weight and carcass gain were higher on the lower level of both roughages. The differences in performance on hay and straw were insignificant. Feed intake was higher on the 15% level of both roughages when pelleted but the energy conversion ratio was higher on pelleted rations of both levels of straw.

The dressing percentage was higher for animals on pelleted rations. There was no significant difference in percentage fat trim, percentage bone or percentage saleable meat in the carcasses. There was 20% more kidney, pelvic and cod fat on the lower level of roughage.

The digestibility of organic matter was higher on rations with the lower level of roughage, and on the pelleted rations compared with the non-pelleted at equal level of roughage. This was not the case for the digestibility of crude fibre. Nitrogen retention was significantly higher on the lower levels of straw and on the pelleted rations of a similar level, and was higher on hay rations than on straw rations. Ration differences in the molar proportions of volatile fatty acids in the rumen liquor were detected.

Pelleting appeared to improve the nutritive value of straw.