Thirty Hereford × Friesian steers initially weighing 320 kg were used in two experiments, to compare the effects of mechanical processing of barley straw and the amount of rolled barley offered on intake and live-weight gain. The straw was offered ad libitum either in the long form or shredded through a 40 mm screen and supplemented with 20, 35 and 50 g barley DM per kgW"75 per day (L, M and H respectively). A solution providing 12 g urea per kg straw dry matter (DM) was sprayed onto the straw and all the animals were offered daily 480 g of soya bean meal with minerals and vitamins. In the first experiment, which had a change-over design, the animals were weighed at the beginning and the end of each period. The daily consumption of shredded straw (kg DM) was L 3·38, M 3·29 and H 3·00 and of long straw L 3·94, M 4·02 and H 3·56 (s.e. of difference, 0·29). There were significant differences in straw intake between steers offered the long and the shredded straw (P < 0·001) but no differences in intake when different amounts of barley were offered within the same physical form of straw. The mean daily live-weight gains for treatments L, M and H respectively were 0·25, 0·66 and 0·80 kg for steers given shredded straw and 0·32, 0·62 and 0·87 kg (s.e. of difference, 0·1) for those offered long straw. At the end of the first experiment the same animals were kept for a further 10 weeks on the same straw treatment but only treatments L and H were continued, the steers from treatment M being distributed between L and H. The straw intakes and live-weight gains were in agreement with those observed in the first experiment

When straw was included in a ration and given to calves from 14 up to 84 days of age, dry matter intake was increased by up to 30 per cent from 1.36 to 1.77 kg per day compared with calves given the diet without straw (Williams, unpublished data). The calves given straw apparently gained an extra 8 kg in weight by 84 days of age compared with calves given the diet without straw. In order to assess the effect of roughage inclusion on the live-weight gains of calves an estimate of the rumen volume of the calves was required. Further since the majority of measurements of the volume of the digestive tract of calves were made after slaughter no studies have described the relationship between diet and the development of rumen volume in individual calves. Differences in rumen volume may be responsible for the large coefficients of variation in intake reported in groups of calves.

Present Welfare Codes recommend systems of dry sow housing which do not involve close confinement. The ‘Pig-code’ system permits automatic individual rationing of group housed sows without the necessity for individual feeding stalls.

The computer controlled feed station has a gating system enabling it to be used by two separately housed groups of sows. On entering, each sow is identified by its collar mounted responder and given any feed remaining from the preset amount for that time period.

There has been much recent interest 1n the Duroc as a possible ‘third breed’ in the UK. In particular, claims have been made that meat obtained from Durocs has high eating quality because of raised levels of intramuscular (marbling) fat. In practice, the Duroc 1s likely to be used 1n crosses involving the ‘white’ breeds. Therefore, in this study, carcass and meat quality were examined 1n Duroc, Landrace and Duroc x Landrace pigs produced contemporaneously.

Twenty-one entire males from each of the breed types were used. Landrace pigs were from a long-established Nucleus population of British Landrace. The Durocs were from a selected Nucleus line, originally established from an importation from Canada 1n 1968, expanded and improved by subsequent North American importations and then extensively upgraded by frozen semen from the USA over the period 1980-85 using a wide range of sires. The D x L progeny were produced alongside the purebreds in the Nucleus. All pigs were fed ad libitum on a ration containing 13.8 MJ DE, 200g crude protein and lOg lysine per kg and slaughtered at approximately 80 kg live weight at the IFR abattoir following a standard pre-slaughter procedure.

The East Friesland breed, developed as a dairy sheep, has a potentially useful role as a sire of first-cross breeding ewes from hill breeds of sheep. Advantages have been shown in terms of reproductive and lactation performance (Doney et al, 1983, Gunn, 1986) but the carcase conformation may reduce the acceptability of first-cross castrated male (wether) lambs. The characteristics of lambs derived from dairy-type breeds may be suitable for the heavy, lean carcase market (Butler-Hogg et al, 1985). The present study was undertaken as a pilot investigation of the potential growth rate and carcase composition of wether lambs over a range of live weights. East Friesland X Blackface (EFB) wethers were compared with a similar group of Border Leicester X Blackface (BLB) and a smaller group of East Friesland X North Country Cheviot (EFC) wethers.

There is little doubt that the lowest costs of beef or milk production are achieved when the animals are grazed on pastures from which they obtain most or all of their sustenance. On the other hand the most expensive phase of cattle production is the winter period when stock are usually housed and must be hand-fed. The results from numerous investigations firmly support these assertions. In the large mixed farming area of the North-East of Scotland virtually no grazing is normally available from the middle or end of October until the beginning of May when normal grass growth has resumed.

Data from 2032 Uruguayan Aberdeen Angus cows under extensive management and recording practices were analysed with Bayesian threshold-liability sire models, to assess genetic variability in calving success (CS), defined as a different binary trait for each of the second (CS2), third (CS3) and fourth (CS4) calving opportunities. Sire (herd) variances ranged from 0.08 to 0.11 (0.10 to 0.20) and heritability from 0.27 to 0.35, with large credibility intervals. Correlations between herd effects on CS at different calving opportunities were positive. Genetic correlation between CS2 and CS4 was positive (0.68), whereas those involving adjacent calving opportunities (CS2–CS3 and CS3–CS4) were negative, at −0.39 and −0.54, respectively. The residual correlation CS2–CS3 was negative (−0.32). The extent of uncertainty associated with the posterior estimates of the parameters was further evaluated through simulation, assuming different true values (−0.4, −0.2, +0.2 and +0.4) for the genetic correlations and changes in the degree of belief parameters of the inverse Wishart priors for the sire covariance matrix. Although inferences were not sharp enough, CS appears to be moderately heritable. The quality of data recording should be improved, in order to effect genetic improvement in female fertility.

Identical group-feeding experiments (each of 90 days duration) were conducted in the summer and in the winter of 1968. The purpose was to study the feed-lot performance of the Grey Shirazi breed on high- and low-concentrate diets with or without diethylstilboestrol (DES) in two different seasons of the year. Lambs on the high-concentrate diet gained more than those on the low-concentrate diet both in summer and in winter. On both diets lambs performed better under cold than under warm conditions. There was no difference when DES was given orally with the above two rations.

During a survey of beef production in East Anglia carcasses of 163 Friesian, 87 Dairy Shorthorn and 45 Aberdeen-Angus × Friesian steers and 44 Aberdeen-Angus × Friesian heifers were measured and scored by visual assessment for fat development. They were also graded by the Ministry of Agriculture, Fisheries and Food.

Age data indicated that the Friesian steers were, on average, younger at slaughter than the other groups, but they were incomplete and comparison was based on carcasses of the same weight. The Dairy Shorthorn steers had higher mean values than Friesians in three of the carcass measurements taken. The Dairy Shorthorns had a higher average fatness score and a higher proportion of Grade A carcasses. Aberdeen-Angus × Friesian steers had lower mean values for measurements of the hind leg, higher fatness scores and a higher proportion of Grade A carcasses than either of the two pure breeds. Aberdeen-Angus × Friesian heifers had lower mean values for measurements of both fore and hind legs, higher fatness scores and a slightly higher proportion of Grade A carcasses than the steers.

The information gained by use of measurements and fatness scores explained, but did not materially add to, the assessment of the relative value of the groups of carcasses given by grade.

Results of two fattening trials, with 49 crossbred ram lambs fattened on an all-concentrate diet given ad libitum with toasted soya bean meal as the main protein source, are presented.

In the first 84-day trial (January to March 1979) there were 32 twin- and triplet-born ram lambs of five genotypes, i.e. Finn-Awassi F2 (FAF 2), Romanov-Awassi F2 (RAF2), Assaf × Finn-Mutton Merino (AsFMM), Suffolk × Finn-Awassi (SuFA) and Suffolk × Finn-Mutton Merino (SuFMM). The overall means ( + s.d.) of the parameters investigated were: initial age, 64·6( + 4·5) days; initial weight, 17·6(±3·0)kg; final weight, 52·2(±4-l)kg; daily gain, 411( + 38)g; food intake, 1·5(±0·3)kg dry matter per day; and food conversion, 3·6( + 0·8)kg dry matter per kg gain.

In the second 56-day trial (August to September 1979) there were 17 single-, twin- and triplet-born FAF2 and Assaf × Finn-Awassi (AsFA) ram lambs. The overall means (±s.d. ) of the parameters investigated were: initial age, 64·1(±8·7) days; initial weight, 24·3(+ 3·6)kg; final weight, 48·5(±5·6)kg; daily gain, 431(±24)g; food intake, l-5(±0·3)kg dry matter per day; and food conversion, 3·5( + 0·7)kg dry matter per kg gain.

In both trials the differences between genotypes in daily gain, food intake and food conversion were not statistically significant and the performance of the progeny of Australian Suffolk and Assaf rams was similar to that of the progeny sired by Finn-Awassi and Romanov-Awassi rams.

Food intake and food conversion were highly correlated with weight of lambs, i.e. r = 0·8864 and r = 0·8857 (d.f. 36), respectively.

In both trials the relationships between daily gain and the pre-fattening performance of the lambs (birth weight, type of birth, weaning age and weight, rates of growth to weaning and from weaning to the start of the trials, as well as the initial age and weight) were not statistically significant.

Braude (1965) has recently reviewed the literature on the subject of supplementation of rations for growing pigs with copper, and concluded that as much as 0·1% copper sulphate could be added to the feed without toxic effects, and that this increased growth rate by about 8·1% and improved efficiency of feed conversion by about 5·4%. Both these values are average responses from a very large number of experiments. Similar results have been reported from the Soviet Union by Volkopjalov, Lebedjeva, Spiridonova and Matuskova (1962).

In a 2 × 2 × 2 experiment, 296 Scottish Blackface ewes were fed to achieve one of two levels of body condition (high: condition scores ^2·75; low: condition scores ^2·50) by 2 weeks before joining with rams. Half of the ewes of each condition score were fed dried grass pellets ad libitum and 300 g hay per head daily, between 2 weeks before and 8 days after joining, while the remaining ewes were offered a live-weight maintenance ration comprising 750 g pellets and 400 g hay per head daily. From 8 days after joining the intake of all ewes was gradually changed, over a 2-week period, to 1250 g pellets and 400 g hay per head daily. Two days before joining, half of the ewes of each condition/intake group were passively immunized against testosterone. A total of 99 ewes were slaughtered 18 days after joining and their ovulation rate at the first mating determined. Ovulation rates were significantly affected by immunization (immunized: 2·31, control: 1·86, pooled s.e. = 0·055; P < 0·01) and food intake (ad libitum: 2·24, maintenance: I 92, pooled s.e. = 0·055; P < 0·05) but not by body condition at mating (high: 2·15, low: 2·02, pooled s.e. = 0·059; P > 0·05). Lambing rates were dependent on treatment (immunized: 1·82 control: 1·62, pooled s.e. = 0·044; P < 0·01), food intake (ad libitum: 1·85, maintenance: 1·59, pooled s.e. = 0·043; P < 0·01) and body condition (high: 1·82, low: 1·62, pooled s.e. = 0·044; P < 001). In ewes in a high body condition at mating, the effects of intake and immunization were additive but in ewes in low condition, immunization induced little improvement in performance in ewes fed ad libitum. Circulating antibody titres were lower in ewes fed ad libitum than in ewes offered a maintenance ration (1: 416 v. 1: 534, pooled s.e. = 14; P < 0·001), but ovulation rates and litter sizes were not related to titres.

To study, after weaning at 6 weeks of age, the effect of age on energy utilization of growing calves and to estimate the requirements of metabolizable energy (ME) for calves weighing less than 100 kg, 243 energy balance trials were conducted using 68 Holstein-Friesian castrated male calves at 7, 9 and 13 weeks of age. Regression analyses of energy retention (ER, kj/kg M0·75) on intakes of ME (kJ/kg M0·75) gave the following equations at the respective age: ER = 0·479 (s.e. 0·070) ME — 197, for 7 weeks, ER = 0·521 (s.e. 0·052) ME - 216 for 9 weeks and ER = 0·523 (s.e. 0·043) ME - 236, for 13 weeks. Amounts of ME for maintenance (MEm) calculatedas ER = 0 were 413, 415 and 451 kJ/kg M0·75 for calves at 7, 9 and 13 weeks of age, respectively. The efficiency of utilization of ME for growth was not significantly different among the ages and was 0·500 (s.e. 0023). ME required for growth was estimated to be 510 kJ/kg M0·75 for each kg gain in weight, irrespective of age. The requirements of ME of calves weighing less than 100 kg were lower than those estimated by extrapolation of British and American standards.

Reproductive data of 139 Simmentaler heifers, previously subjected to different levels of winter and summer nutrition, over a 3-year period, were analysed. Pregnancy rates of 77% and 96% were achieved during the first and second seasons for the two groups of heifers, respectively. Winter and summer nutritional levels affected the number of heifers culled, but had little effect on conception. There were no significant differences in the weight at mating between the heifers that conceived and those that failed to conceive. Mean date of conception was within 30 days and 20 days of the commencement of the breeding season for the first and second season, respectively. Post-weaning nutrition played a relatively minor role in affecting the time of conception. Birth weights of the progeny were not affected by treatment. Calf birth weight was however, significantly (P < 0·05) correlated with the weight of the dam at mating. Sixty-three % of the heifers produced three calves in 3 years, 35% produced two calves in 3 years and only two heifers produced one calf in 3 years. The data supported the original hypothesis that the emphasis, when heifers are bred at 2 years of age, should be shifted away from a physiological base to one where management and grazing strategy are more important in rendering the enterprise economically viable.

The performance of pigs is affected by the rate of nutrient absorption in the gastrointestinal tract, which depends in turn strongly on the rate of stomach emptying. The 13C breath test provides a non-invasive diagnostic tool to measure gastric emptying patterns. Despite the wide acceptance of this method in human intervention studies, it has not found its way to the domain of animal sciences. In this study, we used the breath test to measure gastric emptying in young growing pigs using [1-13C] octanoic acid to trace digesta solids and [1-13C] glycine to study liquids. Pigs were fed a starch-rich diet, varying in starch source (isolated starch from barley, maize or high-amylose maize) or form (isolated barley starch, ground barley or extruded barley), after which 13CO2 enrichment was frequently measured during 11 h. Outliers in 13CO2 enrichment in the response curve of each pig were identified with a Cookʼs distance outlier test in combination with a leave-one-out analysis. Effects of experimental treatments on breath test parameters were tested using a GLM. In general, pigs were easy to train and the tailor-made mask allowed effortless sampling. Gastric emptying of all pigs followed a biphasic pattern, with a higher 13C recovery during the first peak. The first peak in gastric emptying of solids reached its maximum enrichment within 2 h after feeding in all cases. For digesta liquids, this peak was reached earlier for pigs fed ground barley (2.2 h after feeding), compared to pigs fed diets containing isolated starch (2.8 h after feeding). The second peak in gastric emptying of solids was reached later for pigs fed ground barley (5.9 h after feeding), compared with pigs fed extruded barley (4.5 h after feeding) and pigs fed diets containing isolated barley starch (4.8 h after feeding). In conclusion, the 13C breath test is a convenient, non-invasive tool to gain more insights into the gastric emptying pattern of pigs.

Path analysis was applied to correlations among lamb carcass measurements. Correlations were obtained from lamb carcasses averaging 15·7 kg and 270 g fat per kg carcass weight. Correlations were adjusted to represent within breed, sex and management group relationships. The purpose of the analysis was to study the relationships of carcass weight with carcass measurements and to identify carcass measurements that are independent other than through their relationships with carcass chemical fat concentration and carcass weight. The direct effect of live weight on all carcass measurements was positive. Thus, heavier carcasses with the same fat concentration had larger fat and tissue depths, muscle measurements, leg measurements and kidney fat weights. The results of correlations among the residuals suggest that fat depths C and J, specific gravity, muscle width A and kidney fat weight are nearly independent estimates of carcass composition in the sense that they are only correlated through their relationships with carcass weight and carcass fat composition. Robust predictors of carcass composition were developed by first adjusting carcass measurements for the direct effects of carcass weight and then computing regressions on the adjusted measurements. These predictors appeared to be better predictors of environmental and genetic differences than least-squares multiple regression yet reduced the accuracy of within group prediction only slightly.

A Number of controlled environment studies (reviewed by Blaxter, 1962 and 1964) have emphasised the necessity of providing shelter for out-wintered ruminants. The nature of suitable shelter requires definition and this may be sought by observing the use animals make of different forms of shelter. Direct observation of livestock may, however, sometimes be an inappropriate investigational method. In the work reported here, shelter usage by cattle was assessed from the occurrence of defaecations in various regions of a pasture. Evidence of increased sheltering activity under weather conditions encouraging greater body heat loss would suggest that this method of recording behaviour may be recommended for application in relevant situations.