The objective of this study was to further the understanding of the effects of dietary protein and energy supplements on growth, performance, feed intake and grass forage digestibility in growing meat goat wethers. In Experiment 1, an 18% CP complete goat pellet was offered alone (control diet, C) or added (+), or not, as supplement to three grass hays (coastal bermudagrass, CB; Tifton 85 bermudagrass, T; and sorghum-Sudan grass hay, SS), to Boer-cross wethers (n = 72). The resulting seven diets were offered ad libitum. In Experiment 2, four wether goats in metabolism crates were used in a 4 × 4 Latin square design and fed a SS basal diet ad libitum with treatments consisting of no supplement, supplemental urea (200 mg/kg BW daily), supplemental dextrose (0.2% BW daily), or urea + dextrose (200 mg/kg BW daily and 0.2% BW daily, respectively). In Experiment 1, average daily gain (ADG) were −3.8, −5.0 and −6.6 g/day for goats consuming CB, T and SS, respectively, and 69.2, 61.6 and 58.1 g/day for supplemented CB (CB+), T (T+) and SS (SS+), respectively, as compared to 245.8 g/day for ad libitum access to C. Supplementation in Experiment 1 increased (P < 0.01) ADG for all hays when compared to hay-only diets. In Experiment 2, protein and energy supplementation increased (P < 0.01) nitrogen retention but did not impact diet digestibility. The beneficial effects of supplements in Experiment 1 and the increase in nitrogen retention in Experiment 2 cannot be explained by improvements in ruminal fiber utilization, but could be due to post-ruminal nutrient supply and/or increased ruminal microbial protein synthesis.

Early lactation parameters are difficult to estimate from commercial dairy records due to the small number of records available before the peak of production. A biological model of lactation was used with weekly milk records from a single Holstein herd to estimate these early lactation parameters and the secretion rate of milk from the average cell throughout lactation. A genetic analysis of the lactation curve parameters, calculated curve characteristics and secretion rate traits was undertaken. Early lactation traits were found to have little genetic variation and effectively zero heritability. Secretion rate traits for milk, protein, lactose and water were all moderately heritable and highly genetically correlated (>0.87) but fat secretion rate had lower genetic correlations with the other secretion rates. A similar pattern of correlations was seen between total lactation yield traits for fat, protein, lactose and water. The genetic correlations between the lactation curve traits and the secretion rate traits were calculated. Total milk yield, peak yield and maximum secretion potential were all highly correlated with milk, lactose and water secretion rates but less so with fat and protein secretion rates. In particular, fat secretion rate had a moderate to low genetic correlation with these lactation curve traits. Persistency of lactation was highly correlated with fat and protein secretion rates, more persistent lactations being associated with lower rates of secretion of these milk components. Similar levels of heritability were found, where trait genetic parameters were directly equivalent to those derived from the same dataset by random regression methods. However, by using a biological model of lactation to analyse lactation traits new insights into the biology of lactation are possible and ways to select cows on a range of lactation traits may be achieved.

The prediction of grass dry matter intake (GDMI) and milk yield (MY) are important to aid sward and grazing management decision making. Previous evaluations of the GrazeIn model identified weaknesses in the prediction of GDMI and MY for grazing dairy cows. To increase the accuracy of GDMI and MY prediction, GrazeIn was adapted, and then re-evaluated, using a data set of 3960 individual cow measurements. The adaptation process was completed in four additive steps with different components of the model reparameterised or altered. These components were: (1) intake capacity (IC) that was increased by 5% to reduce a general GDMI underprediction. This resulted in a correction of the GDMI mean and a lower relative prediction error (RPE) for the total data set, and at all stages of lactation, compared with the original model; (2) body fat reserve (BFR) deposition from 84 days in milk to next calving that was included in the model. This partitioned some energy to BFR deposition after body condition score nadir had been reached. This reduced total energy available for milk production, reducing the overprediction of MY and reducing RPE for MY in mid and late lactation, compared with the previous step. There was no effect on predicted GDMI; (3) The potential milk curve was reparameterised by optimising the rate of decrease in the theoretical hormone related to secretory cell differentiation and the basal rate of secretory cell death to achieve the lowest possible mean prediction error (MPE) for MY. This resulted in a reduction in the RPE for MY and an increase in the RPE for GDMI in all stages of lactation compared with the previous step; and (4) finally, IC was optimised, for GDMI, to achieve the lowest possible MPE. This resulted in an IC correction coefficient of 1.11. This increased the RPE for MY but decreased the RPE for GDMI compared with the previous step. Compared with the original model, modifying this combination of four model components improved the prediction accuracy of MY, particularly in late lactation with a decrease in RPE from 27.8% in the original model to 22.1% in the adapted model. However, testing of the adapted model using an independent data set would be beneficial and necessary to make definitive conclusions on improved predictions.

Fully slatted concrete floors are labour-efficient, cost-effective and thus common in beef cattle housing. However, the welfare of cattle accommodated on them has been questioned. The objective of this study was to evaluate the effect of floor and diet on hoof health and lying behaviours of housed dairy-origin bulls, from a mean age of 8 months to slaughter at 15.5 months old. Forty-eight bulls, which had a mean initial live weight of 212 (SD = 23.7) kg, were allocated to one of four treatments, which consisted of two floors and two diets arranged in a 2 × 2 factorial design. The floors evaluated were a fully slatted concrete floor and a fully slatted concrete floor overlaid with rubber, while the diets offered were either a high concentrate diet or a grass-silage-based diet supplemented with concentrates. The mean total duration of the study was 216 days. Floor had no significant effect on claw measurements measured on day 62 or 139. However, bulls accommodated on slats overlaid with rubber had a tendency to have a higher front toe length measured pre-slaughter than those accommodated on concrete slats (P = 0.063). Floor had no significant effect on the net growth of toes or heels during the duration of the study. The number of bruises (P < 0.01) and the bruising score (P < 0.05) were significantly higher on day 62 in bulls accommodated on fully slatted concrete floors than on concrete slats overlaid with rubber, but there was no significant effect of floor on these parameters on day 139 or at the measurement taken pre-slaughter. There was a tendency for bulls accommodated on concrete slats to have a higher probability of having sole bruising at the end of the experiment than those accommodated on slats overlaid with rubber (P = 0.052). Diet had no significant effect on toe length or heel height, number of bruises, or overall bruising score at any time point of the study. There was little evidence in the current study to suggest that bulls lying on fully slatted concrete floors could not express lying postures similar to those on concrete slats overlaid with rubber.

The growth rate and body composition of lambs depend on their rate of feed intake and the composition of the feed given. The purpose of the experiment described here was to test predictions of the growth and composition of lambs given feeds of two protein contents at three levels of feeding.

73 Scottish Blackface wethers were abruptly weaned at 49 days of age and an average live weight (LW) of 18 (sd 2.2) kg. Six, chosen to cover the range in initial liveweight, were killed and those remaining were put into individual pens and fed in one of six ways. Two feeds with 140g CP/kg fresh weight (FW), called LP, and 220 g CP/kg FW, called HP, were used. They were formulated using barley, maize and soyabean meal, and hay at 150g/kg FW, and were calculated to yield 11.8 MJ ME/kg FW. Each feed was given ad libitum (AL) and at daily rates of 1.2 or 0.8 kg FW. The numbers of sheepstarted were: ALHP, n = 8; ALLP, n = 8; 1.2 HP, n = 12, 1.2 LP, n = 13, 0.8 HP, n = 14, 0.8 LP, n = 12. Sheep were killed from each treatment at 5 kg LW intervals from 25 to 50 kg. After slaughter the weights of gut-fill and organs were taken and the carcase physically dissected into lean, bone and fat. The chemical composition - dry matter and the ash, N, lipid and gross energy contents of the dry matter - of the whole empty body, excluding wool, was measured. Wool weights were determined. The intakes and weights of each sheep were measured twice weekly.

The new concern in Britain which links diet to health is likely to have a major impact on the agricultural and food industries. Five years ago consumers were not interested in the health issue but now consumer groups are lobbying for change. Health has become the second most important factor considered by a housewife when shopping for her family, the first being whether the food is appetizing.

Both the DHSS and MAFF have accepted, the 1984 COMA panel's report on diet and cardiovascular disease which sets out a programme of preventive measures with recommendations to the general public, medical practitioners, health educators, food producers, manufacturers, distributors and caterers and to Government. Specific changes in the British diet are advocated for the first time with a suggested reduction in saturated fat intake of 25% and in total fat of 15%.

The test proofs of 29 Holstein-Friesian sires (12 Canadian and 17 US) with milking daughters in both Canada and the USA were compared. The mean test rating of the Canadian and US sires respectively was 125±74 kg and 265±57 kg higher in Canada than in the United States.

These results were supported by others obtained in milking trials in Denmark and West Germany.

The fat percentage of US Holstein progeny was higher in Canada and Europe than in the USA, suggesting that the low fat percentage of the US Holstein in its country of origin cannot be attributed simply to lack of genetic potential.

It is suggested that the US Holstein be considered as a substitute for the Canadian for the improvement of milking performance in European Friesian populations.

The relative performances of crossbred ewes sired by Finnish Landrace or by non-Finnish rams were measured in trials at 18 farms which yielded a total of about 2600 ewe lambing records. The dams of the crossbred ewes were Hill breeds (40%), Upland (22%), Long-wool x Hill (20%) and other breed types (18%). The non-Finnish sires were Longwool breeds (35 %), Down and Down crosses (33 %), Upland (22%) and other breeds (10%).

Finnish crossbred ewes were lighter at mating than the average of non-Finnish crossbreds by 10% at 7 months, increasing to 24% at 31 and 43 months, with an average difference of 18% for the first 4 years of life. Over the same period of 4 years Finnish crossbreds had a 27 % higher lambing percentage and 21 % higher weaning percentage than non-Finnish crossbreds.

Lambs born to Finnish crossbreds were, over the 4-year period, 16% lighter for singles and 20 % lighter for multiples at birth, and 11 % for single born and 12% for multiple born at 10 weeks, than those born to non-Finnish crossbreds. But the total litter weight of lamb reared to 10 weeks per 50-kg metabolic ewe weight (at mating) was 16% more for Finnish crossbreds than for non-Finnish crossbreds.

The efficacy of feed additives in enhancing the performance of growing pigs, together with the effect of different protein levels (18 v. 16% from 13 to 18 kg body weight and 16 v. 14% from 18 to 39 kg body-weight), were evaluated in three experiments with 412 pigs. In Experiment 1, from 13 to 39 kg body weight, pigs receiving 55 p.p.m. carbadox (C) produced a greater (P<0·05) average daily live-weight gain than did the non-medicated (NM) pigs and those receiving 275 p.p.m. chlortetracycline-sulphamethazine-penicillin (ASP) with a similar but non-significant (P>0·05) trend n i daily feed intake and gain/feed ratio. The ASP pigs also produced a greater (P<0·05) weight gain than the NM pigs. The higher dietary protein level sequence produced a greater (JP<0·05) weight gain and gain/feed ratio.

In Experiment 2, from 16 to 39 kg body weight, NM control pigs achieved high weight gains, and all the feed additive treatments studied [C+106 p.p.m. of the worming agent pyrantel tartrate (C+P); ASP+8 mg of the worming agent levamisole-HCl per kg body weight fed once on day 7 of the experiment (ASP+L); and 113 p.p.m. tylosin+13 p.p.m. of the worming agent hygromycin B] were similar to the NM controls in daily feed intake, weight gain and gain/feed ratio. However, in Experiment 3, the C+P and ASP+L treatments resulted in a greater (P<0·05) weight gain with a trend toward greater daily feed intake than did the NM control treatment from 17 to 35 kg. The weight gain of the ASP+L pigs was also greater (P<0·05) than that of 165 p.p.m. oxytetracycline and NM pigs from 35 to 57 kg. From 57 to 96 kg all the pigs received the same NM control diet and their weight gains were similar. The gain/feed ratio was similar among the treatments within each of the weight periods in Experiment 3. Pigs slaughtered at the beginning and at various stages during Experiments 2 and 3 were free of internal parasites and migration damage.

It is well established that the genetic merit of the Holstein-Friesian dairy cow for milk production has increased over the past 20 years. Previous studies have examined the effect of feeding system on indices of body tissue reserves of medium genetic merit Holstein-Friesian dairy cows. The aim of the current study was to examine the weight and concentration of body components in high genetic merit Holstein-Friesian dairy cows, managed on four different grassland-based feeding regimes, using direct measures of body composition. Results indicate that there was no significant effect of different grassland-based feeding regimes on the weight or composition of body components of high genetic merit cows. Therefore, high levels of cow performance can be sustained from very different grassland-based systems of milk production without having a detrimental effect on body tissue reserves.

In populations where generations overlap and initial genetic differences between age groups differ from steady-state values, genetic responses fluctuate in the early years of a selection programme. The degree of deviation of these selection responses from steady-state responses indicates the usefulness of estimates of economic returns calculated more simply using the steady-state value. Here these deviations and their effect on sums of discounted returns are first defined and the models derived then used in numerical analysis. Some problems of definition of these deviations are discussed.

The results showed that deviations from sums of discounted returns calculated using steady-state responses varied from about −1% when starting conditions were similar to steady-state conditions to more than 20% when initial genetic differences between age groups were taken as zero. Increases in discount rate increased the effect of the deviations from uniform response while the effect of changing age structure was unpredictable. As initial genetic differences between age groups increased, deviations were increasingly positive among selection methods which made better use of those differences.

The variation of protein fractions in the milk of indigenous Greek goats fCapra prisca) during the milking period was studied. Total nitrogen (TN), non-casein or soluble nitrogen (SN), rennet whey nitrogen (WN), non-protein nitrogen (NPN) were determined and from these analyses crude protein (CP), true protein (TP), casein (Cas) rennet casein or coagulable protein (Coag P) were calculated. The NPN component is lost during the cheese process whereas Cas and Coag P are important constituents of the cheese itself. The ratios NPNICP, CaslTP and Coag PITP throughout milking, were for the groups A and B 0·0646 and 0·0648 (s.e.d. = 0·00025), 0·846 and 0·845 (s.e.d. = 0·0141) and 0·916 and 0·904 (s.e.d. = 0·0112), respectively, suggesting a high level of suitability for conversion of milk into cheese.

With the objective of studying the response patterns of two biotypes of different body (structural) size to stocking rate (SR) in terms of individual growth rate (ADG), meat production per ha (PROD) and backfat thickness (BFT) under grazing conditions, 64 steers of two biotypes of the Angus breed of different body size were used: small-sized (SB: frame score of 1·3 (s.d. 0·7)) and medium-sized (MB: 2·9 (s.d. 0·6)). Four levels of SR were applied (1·8, 2·3, 2·8 and 3·3 steers per ha). The experiment lasted 241 days (April to December). Animals were weighed every 14 days, forage availability (FA) was estimated on four occasions and BFT was recorded at the end of the experiment (between 12th and 13th ribs). There were no differences between biotypes in ADG. SB tended to be earlier maturing showing higher BFT (4·39 v. 3·97 mm; P = 0·22). ADG was affected by SR and was higher at lower SR (0·612, 0·529, 0·414 and 0·375 kg/day, for 1·8, 2·3, 2·8 and 3·3 steers per ha, respectively). Individual average daily gain of the MB was more variable across the seasons of the year. None of the variables showed effects of the biotype × SR interaction but differences in ADG between biotypes as a function of the SR were observed as a trend (P = 0·29). Despite the difference in frame score between biotypes it was not possible to associate it with consistent differences in the response variables. Individual productivity (potential) of MB was not reflected in a greater productivity per surface unit. The data from this experiment do not allow the choice of a particular biotype in order to optimize the productivity of the pastoral production systems.

Breed means are given for 40 traits relating to food conversion efficiency and body composition at the same stage of maturity in seven breeds of sheep and a feral goat breed. In terms of breed means, food intake and food conversion efficiency were genetically correlated, as were most traits associated with fatness or leanness.

Highly inter-correlated measures of breed fatness were proportion of fat in the carcass, proportion of total carcass fat found in the rib plus loin, the fat : muscle ratio and the lipid concentration in the dry matter of all tissues except bone. Dressing proportion was highly correlated with all these measures of fatness.

Breeds with a high proportion of subcutaneous fat did not necessarily have a low proportion of intra-abdominal fat. A low proportion of carcass fat in the rib plus loin was associated with a high proportion in the shoulder (inter-breed correlation —0·7): both were measures of leanness. Muscle : bone ratio was not correlated with fatness or leanness. Slower maturing, larger breeds had slightly more bone, less fat and more lean in their higher-priced cuts. Breeds with heavier fleeces were fatter (0·7). The food conversion efficiency of a breed was largely independent of its body composition.

Imported semen from 10 Italian Chianina bulls was used to inseminate beef and dairy cattle throughout England and Southern Scotland. A total of 2134 records of calving performance were subjected to least squares analyses. Dystocia score was significantly affected by county of birth, parity of dam, sire, type of birth, birth weight (P < 0·001), season of birth and sex of calf (P < 0·01). There were no significant effects of breed or size of cow. Serious dystocia was encountered in 3% of calvings, with the incidence for individual sires ranging from 1·7% to 6·7%. Arithmetic mean gestation length was 284·2 days and it was significantly affected by county, sire (P < 0·05), sex of calf (P < 0·01), and type of birth (P < 0·001). Arithmetic mean birth weight of the calves was 41·2 kg and this was significantly affected by all main effects studied except season of birth and type of herd.

The optimal balance of amino acids in the diet of the growing pig was estimated by ARC (1981) on the basis of a number of disparate studies augmented by data on the amino acid composition of the whole body on the premise that the amino acids incorporated into accreted body proteins are the major determinant of requirements and that this pattern is not distorted by inequalities in the utilisation of individual amino acids. In an accompanying paper (Wang & Fuller, paper no. 91) an optimal pattern was derived by direct experiment which was shown to be utilised better than that described by ARC (1981). That pattern, however, which related to one particular rate of nitrogen input and the particular rate of protein accretion which that input supported, includes two components, a requirement for maintenance and a requirement for protein accretion. There is clear evidence from studies with rats and chicks that the optimal pattern of amino acids for maintenance and growth are quite different and so the optimal pattern for any particular rate of growth will depend on the relative contributions of the two components. The purpose of this experiment was to estimate both.

Random regression (RR) analysis has been recommended to estimate the genetic parameters of longitudinal data. The objective of this study was to evaluate the growth of turkeys using RR models. Data were collected from 957 turkeys and included 15 478 individual body weight recorded during the first week of life and between weeks 2 and 32 by 2-week intervals. To take into account the repeated measurements of weight for each animal, a specific overall growth curve was modelled using a cubic smoothing spline. Animal deviation to this curve was also modelled using an RR function. All data were analysed with the ASReml package. The results showed an increase in heritability estimates over the trajectory and peaked at 0.60 around 20 to 32 weeks of age. Genetic correlations showed that turkeys could be selected at earlier time points, at 12 weeks of age, in order to increase the growth rate. In general, genetic correlation estimates were higher among adjacent ages, decreasing markedly with the increase of distance between ages. Negative genetic correlations were observed between ages.

Insulin plays an important role in regulating the partitioning of nutrients to the mammary gland, particularly in lactating ruminants fed concentrate-based diets. There is evidence that the nutritional status of the animals might also affect their response to insulin. This is largely untested in early lactating ruminants fed fresh forage. To investigate nutritional effects on insulin response, 12 lactating sheep, housed indoors, were allocated to one of two treatment groups (hyperinsulinaemic euglycaemic clamp (HEC) or control) in a randomised block design and fed perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture. Mammary amino acid (AA) net uptake from plasma and utilisation for milk protein synthesis was measured during the 4th day of the HEC using arterio–venous concentration differences, and 1-13C-leucine was used to estimate whole body and mammary gland leucine kinetics. There was no change in feed intake, milk protein output and mammary blood flow during the HEC (P > 0.1). The HEC decreased (P < 0.1) the arterial concentrations of all essential AA (EAA) except histidine. The mammary net uptake of some EAA (isoleucine, leucine, methionine and phenylalanine) was reduced by the HEC (P < 0.1). Leucine oxidation in the mammary gland was not altered during the HEC (P > 0.1) but mammary protein synthesis was reduced by the HEC (P < 0.05). These results show that sheep mammary gland can adapt to changing AA precursor supply to maintain milk protein production during early lactation, when fed fresh forage. How this occurs remains unclear, and this area deserves further study.

Consumer reaction to bacon from boars and castrates, whose production and processing characteristics were known, was determined in 122 households consisting of 238 respondents. On a seven-point scale the mean scores for six organoleptic characteristics were similar for each sort of bacon relative to that usually purchased. A proportion of 0·045 of cooks scored boar bacon at the point of strongest rejection (unappetizing aroma) during cooking but less than 001 considered that the flavour was very much stronger than their usual bacon. Few respondents marked boar bacon inferior to their usual bacon for eating characteristics. On a comparative basis the frequency distribution of scores for flavour, juiciness and pleasantness of aroma on the plate was slightly in favour of castrate bacon but was of little importance. Using the production and processing data obtained and accepting no adverse consumer reaction to boar bacon, a financial advantage to the producer of entire male pigs for bacon manufacture over castrates was demonstrated (£2·95). However, if the retailer should not reward the curer for the extra leanness of the boar then the curer might be at a financial disadvantage.

A dynamic simulation model was used to predict the long-term effects of published heat stress-associated fluctuations in conception rate (CR) and milk production (MP) on the monthly MP pattern in Israel. The model results showed that the pattern of seasonal decline and rise in CR, and hence conception occurrences, produces a similar pattern of MP. This pattern closely resembles that of actual MP in Israel in 1987 and in 1988. On the other hand, seasonal correction factors for MP have no marked effect on the shape of the MP curve. These results show that in order to stabilize MP throughout the year, the prevention of seasonal (summer) decline in CR would be more effective than direct efforts to prevent seasonal MP decline.