The influence of the physical structure level in the diet on animal performance was investigated in 52 Belgian Blue doublemuscled bulls starting from a live weight of 348 kg until slaughter at about 645 kg. Four diets with different concentrate/maize silage ratios were offered ad libitum. The structural value (SV), developed in Belgium as a measure of physical structure in the diet for dairy cows, amounted to respectively 0.63 (HSV; high SV), 0.54 (MSV; moderate SV), 0.43 (LSV; low SV) and 0.34 (VLSV; very low SV) per kg dry matter.

Growth rate, food intake and food conversion were all linearly affected by the decreasing SV of the diet. Among carcass parameters only the SEUROP conformation score showed a significant effect of the SV, with the MSV group having the highest score and VLSV the lowest. No important influence of the SV on the histological damage of the ruminal papillae or on the foot lesions was found.

Based on the lower growth rate and food intake of the LSV group versus the HSV group, a SV of the diet between 0.54 and 0.43 is considered as an absolute minimum for Belgian Blue double-muscled bulls.

The linear growth rate of wool on three sites on each of six Wenslcydale × Blackface lambs was measured by wool fibre autoradiography following 11 injections of 35S-cystine. The first injection was given at 09.00 h, so that alternate 36h intervals between injections represented predominantly day (09.00 to 21.00h) or night (21.00 to 09.00 h). The overall mean growth rates on shoulder, mid-side and breech were 0·83, 0·96 and 0·95 mm/day. Differences between day and night growth rates were very small (proportionally<0·05) and inconsistent in 16 of the 18 samples; although breech samples from two sheep showed up to 0·14 faster growth in daytime, a circadian rhythm of wool growth seems unlikely on this evidence. Both linear wool growth rate and food intake increased steadily throughout the experiment.

Mid-side wool growth rates in a second group of three crossbred longwool lambs averaged 0·79, 100 and 1·14 mm/day and were relatively stable over a period of several months.

Low levels of antibiotics have been used in animal diets since the 1950’s to improve growth rates by stabilising the gut flora. At higher levels antibiotics have also been used as prophylactics against enteric diseases.

As a result of growing public concern of the the indiscriminate use of antibiotics in the animal industry there are now strict controls on their use. An alternative approach to the use of antibiotics in the control of the gut flora is the use of what have become known as probiotics. Probiotics include viable lactobacillus bacteria cultures and fermentation products which actively colonise the gut wall, and suppress further colonisation by potential pathogens such as virulent E. coli organisms. At times of stress in an animal’s life, such as weaning or re-grouping, the oral application of probiotic agents could be beneficial by both preventing disease and minimising the clinical use of antibiotics.

Early-weaned artificially-reared piglets are particularly at risk to enteric disease and therefore the purpose of the present study was to assess the efficacy of a probiotic agent in pigs weaned at 6 hours of age.

A further experiment in a series of trials to look at the effects of treating straws on their feed values, and the responses to different supplements was carried out in the winter of 1982-83. The treatments were:-

1. 1) Untreated barley straw (DBS) plus 1.5 kg rolled barley/urea per day

2. 2) Ammonia treated barley straw (TBS) alone

3. 3) Ammonia treated wheat straw (TWS) alone

4. 4) Ammonia treated wheat straw (TWS) plus 0.5 kg rolled barley

5. 5) Ammonia treated wheat straw (TWS) plus 0.5 kg soya bean meal

6. 6) Ammonia treated wheat straw (TWS) plus 0.25 kg rolled barley and 0.25 kg fishmeal

There were 7 Hereford x Friesian cows per treatment, all mature animals (third calvers or more) calved in May, bulled with a Charolais bull in July and calves weaned off and cows yarded in November 1982. The trial ran for 145 days from 25 November 1982 to 19 April I983 covering about months 4 to 8 of pregnancy. They were group fed.

For the past 20 years specialised sire and dam lines have generally exploited existing breed differences, and there has been little within-breed selection for litter size. However, some lines may now be approaching optimum fatness. At the same time, more accurate methods are evolving for estimating genetic merit for litter size. This study therefore re-examines the benefits of selection for litter size in specialised dam lines.

Little objective information is available on the relative merits of straw based and slatted floored systems for the weaned pig in terms of performance and indices of welfare. A controlled experiment was conducted in an attempt to obtain relevant information.

The following 3 systems were compared: (1) straw bedded pens (SB), conventional flat decks (FD) and identical flat decks with environmental enrichment (FD+). The FD pens had fully perforated expanded metal floors with an ad lib feeder across the front of the pen and 2 nipple drinkers on the opposite wall. The enriched FD pens had a variety of ‘recreational’ objects added - a metal chain and tyre suspended from the ceiling within the pigs’ reach, a concrete block, a tyre and an assortment of rounded stones of different size placed on the pen floor. There were 3 pens per room but only 2 were used in the trial, one each for the FD and FD+ treatments. Temperature control was by means of 2 gas heaters and a fan assisted ventilation system which was thermostatically controlled. The straw pens were located in a large cattle court which had a concrete floor; within each pen there was a kennelled lying area and an open outrun. The whole floor surface was kept liberally covered with good quality dry barley straw. An identical ad lib feeder to that in the flat decks was provided in the outrun area and 2 nipple drinkers were provided adjacent to the feeder. In all treatments for the first 3 days of the trial a box drinker was placed in each pen to allow the pigs time to familiarise themselves with the nipple drinkers.

Premature loss of wool from fleece casting prior to shearing is a problem in some sheep genotypes, in particular in the North Country Cheviot. The reasons for this ocurrence are not fully understood, but it is believed that it is due to a complex of factors including heredity, nutritional and managerial (stress) practices, the wool growth cycle, and physiological parameters such as pregnancy. Prolonged stress is reported to be particularly important in the case of wool slip in ewes which are housed and shorn (Morgan et al, 1986).

The present study aimed to investigate the incidence of visible fleece casting in the North Country Cheviot (NCC), Scotch Halfbred (HB) (Border Leicester x NCC), and Border Leicester (BL), which has no history of premature wool loss. The study was implemented on 8 commercial farms in Scotland, and links between key productive parameters and wool loss were studied, and an attempt to identify fleece types most liable to cast was also made.

In farmed salmonids the majority of consumed nitrogen is lost in metabolic waste products (mainly ammonia) and the faeces (Table 1). Any improvement in nitrogen retention, brought about by reductions in these components, would decrease environmental load. Inter-individual variation in retained nitrogen has been little investigated as a basis for selection of more efficient fish; this communication points to an experimental approach to measuring individual variation by concentrating on digestive efficiency and protein turnover as possible contributors to nitrogen retention. The utilization of dietary nitrogen was investigated in two species of farmed salmonid, the rainbow trout, Oncorhynchus mykiss and the Atlantic salmon, Salmo salar.

Manipulation of the bacterial population of the intestine has been shown to result in changes in the structure and function of mucosal tissues. The objective of the present experiment was to investigate the effect of inclusion of a non-therapeutic antibiotic, virginiamycin, in the diet of sheep on the activity of the Na* -dependant transport of glucose and alanine by enterocyte cells. These transport mechanisms can be studied by isolation of brush border membrane vesicles following sub-cellular fractionation of the mucosal tissues.

Tissue was obtained from two separate growth trials in which the effect of inclusion of virginiamycin on lamb growth was being studied. In Trial 1 (glucose studies) the animals had been fed a concentrate diet plus hay ad libitum and virginiamycin was included at 100 ppm in the treatment group. In Trial 2 (alanine studies) the sheep were fed a concentrate diet with virginiamycin included at 50 ppm in the treatment group.

Leg disorders in male turkey breeding stock are associated with pain during locomotion (Duncan et al 1990). Musculo-skeletal diseases are prevalent in broiler breeder males and the experiment was designed to evaluate birds of two ages for evidence of pain during movement. Two experiments were conducted, the first examined differences in sexual motivation and the second the rate of walking towards a food reward. At the end of the experiment the birds were killed and the legs dissected to establish the presence of musculoskeletal disease.

Commercial broiler breeder males were housed singly with 15 females in 4 rooms each containing 12 floor pens measuring 1.5 x 2.4 m. There were 24 males in each of two age groups (40 and 60 weeks at the start of the experiments). To determine sexual motivation, males were removed to an empty pen in a spare room. They were returned after 3-5 h and observed for 15 min. The time to make a sexual approach (AP) and to mount a female (MT), and the number of copulations were recorded on three different days. Subsequently, males were trained to walk through a 20 m long alley constructed of hardboard to receive their daily food allocation. During testing, the time taken to reach the food was recorded 3 times before the male was returned to its pen. The males in two rooms were used in a 2-period crossover experiment to evaluate the effects of naloxone (an opiate receptor antagonist) and three analgesics on walking speed (Table 1). All measurements of time were transformed to natural logarithms for analysis. A censored analysis was used for AP and MT. The total number of copulations observed (COP) was modelled using Poisson errors. The models included effects for age and day (where appropriate). The data were reanalysed with the lesion score as a fixed effect. The initial model for walking speed included period and carry over effects. Mixed model methods (REML) were used to assess the final model with birds as blocks and treatment and lesion as main effects.

Energy intake and nitrogen balance studies have been conducted on 12 lambs fed ad libitum on four all-concentrate diets of equal crude-protein content in an experiment of latin square design. Each diet contained one cereal, either barley or oats and one protein supplement, either white-fish meal or soya bean meal.

Protein supplements had no influence on energy intake, but intake was significantly higher when the lambs were given barley rather than oat diets.

There were highly significant differences in the degree of utilization of digested nitrogen between diets containing fish meal and soya bean meal, and between diets containing barley and oats.

The energy: nitrogen ratio of urine was inversely related to the proportion of urinary nitrogen present as urea and directly related to the degree of utilization of digested nitrogen.

Least squares analyses were undertaken on 1519 gestation lengths of cows mated to Beef Shorthorn, Hereford, Charolais, German Simmental or British Friesian bulls. Gestation length was influenced largely by breed of sireand byindividual sires within breeds. Approximately 100 calvings are required to give a mean value with a standard error of 0·50 day. Heritability of gestation length was estimated to be 0·24±0·05. It is recommended that Artificial Insemination organizations survey and publish the mean gestation lengths of their bulls and that dairy farmers modify, where necessary, pre-partum feeding in the light of this information.

The efficiency of part lactation test day (TD) records in first parity for the genetic evaluation of bulls and cows using a random regression model (RRM) and a fixed regression model (FRM) was studied, modelling the random and fixed lactation curves by Legendre polynomials. The data set consisted of 9 242 783 TD records for first lactation milk yield of 1 134 042 Holstein Friesian heifers. The efficiency of both models with part lactation TD records was examined by comparing predicted transmitting abilities (PTAs) for 305-day milk yield for 114 bulls and their 4697 daughters, from analyses where the maximum number of TD records of these daughters was restricted to the initial 2, 4 or 6 TDs with those estimated from 10 TDs. The correlations of PTAs estimated from 2, 4 or 6 TDs with those from 10 TDs computed for cows and bulls within each model were very similar. A rank correlation of 0·91 (0·92 FRM) was obtained for cows between PTAs based on 2 TDs and those from 10 TDs. The correlation increased to 0·96 with 4 TDs and 0·98 with 6 TDs. For bulls, correlations between PTAs estimated from 4 or 6 TDs with those estimated from 10 TDs were high at 0·98 and 0·99 respectively. With 2 TDs, the correlation was 0·95. The average under-prediction of PTAs with 2, 4 or 6 TDs relative to 10 TDs was generally higher and more variable with a FRM compared with a RRM for highly persistent cows and bulls. A similar trend was observed for mean over-prediction of PTAs, except for the initial predictions based on 2 TDs when the RRM gave a higher mean over-prediction for bulls and their daughters with low persistency but high initial TD records. The range of over and under-predictions were large (up to 200 kg milk) for some bulls when only 2 TDs were included in both models. A moderate correlation of 0·64 was obtained between persistency evaluations estimated from 10 TDs with those estimated from 2 TDs. The correlation increased to 0·71 with 4 TDs included and 0·85 with 6 TDs. The moderately high correlation between 6 TDs and 10 TDs of 0·85 was unexpected given the high correlation of 0·99 between PTAs for yield estimated from 6TDs with those estimated from 10 TDs.

Sibs of five to 11 twin pairs each of five breeds were either slaughtered as veal or as yearling bulls. Highly significant breed differences were evident in the carcass tissue proportions which could be explained on the basis of differences in the physiology of dairy and dual-purpose animals, the former depositing more fat and more bone than dual-purpose breeds. Among the dual-purpose breeds the carcasses of the Pinzgauer (Pi) tended to rank between the carcasses of the Fleckvieh (FV), Braunvieh (BV), Grauvieh (GV) and those of the Friesian (Fr).

The dual-purpose breeds FV, BV, GV had more meat in the hindquarter and in the shoulder than the FR while these in turn had more meat in the brisket and in the flank and shank muscles. Again the Pi group tended to rank between the aforementioned groups.

Within breeds, large differences between twin pairs indicated high heritabilities for carcass tissue proportions and ratios. The heritability of commercial cut proportions was fairly high but the genetic variance was small, the genetic coefficient of variation being less than 0-02. The different degrees of sexual maturity and of carcass maturity also caused differences in the distribution of meat in the carcasses of young male animals.

Significant mean squares for interactions between treatments and breeds, and genetic correlations of less than unity between performance of twin genotypes in veal and in bulls, indicated age and/or rearing system by genotype interactions between and within breeds for various slaughter traits.

Phenotypic correlations between various slaughter traits were low except where part-whole relationships were involved. It is suggested that slaughter at comparable maturity in the respective treatments was the cause of the weak connection between the traits.

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.

1. In a randomized block experiment 72 Large White-type pigs (in pens of six) were individually fed twice daily on six variations of a basic diet containing 80% barley, 15% soya bean meal (S) and 5% of a vitamin-mineral supplement (VM).

2. For treatments 1 to 3 the pigs were given both supplements together. The combined supplement was either mixed with the barley (treatment 1—control), or added to the barley at either both meals of the day (2), or at only the morning meal (3). For treatments 4 to 6 the supplements were given separately. For treatment 4, VM was given at the morning feed and S in the afternoon; for treatment 5, VM was given at both feeds of one day and S at both feeds of the next day, for treatment 6 the supplements were given only at the morning feeds, VM on one day followed by S on the next day.

3. Overall, there were no significant differences between treatments 1 to 5 in growth rate or efficiency of food conversion. The pigs on treatment 6 refused a relatively large percentage of their food, grew significantly more slowly but converted their food significantly more efficiently than did the pigs on any of the other treatments. There were no significant differences between treatments in any of the carcass data recorded.

In each of 4 years, 24 autumn-calving, single-suckling Aberdeen Angus × Friesian cows with Charolais cross calves were subjected to different winter feeding regimes and to a range of weaning dates, and the effect on cow and calf food intake and performance was measured. Giving 257 kg concentrate dry matter to cows on an ad libitum silage diet over winter increased calf and cow weights in the following September by 17·8 and 11·7 kg respectively. Weaning after 4 months of lactation resulted in a net saving in winter forage requirements when compared with weaning in March/April but a high input of concentrate was necessary to achieve satisfactory calf performance. Weaning in July increased calf weights in August/September by 22·1 kg and reduced cow weights by 22·3 kg compared with weaning in March/April. Later weaning at pasture might be preferable, producing heavier calves, provided that cow weights can be restored at pasture.

The application of ultrasonics to the evaluation of live cattle has been carried out in bull performance testing for several years. The machine used for this was the Scanogram. The fact that this machine is no longer being produced and the emergence of several new machines has prompted this trial to evaluate seven ultrasonic machines.

A total of 49 bulls, 27 Limousin x Friesian and 22 Charolais x Friesian, were evaluated and slaughtered in four batches of approximately equal size, over four weeks. Each batch was of one breed.

Age, live weight at evaluation and subjective assessments of fatness and conformation were recorded together with fat and muscle measurements by the Delphi (Delphi Instruments Ltd, New Zealand), Meritronics (Merit, Lowson and French, England), Scanogram (Ithaco Incorporated, USA), Vetscan (Company no longer in existence), Kaijo Denki (Medata Systems Ltd, England), Velocity of Sound (Prototype developed at IFR-Bristol, England) and Warren (Prototype developed by J Warren) ultrasonic machines.

It is not clear when the optimum time of harvesting the winter barley as whole crop for silage should be in terms of feeding value for dairy cows and yield of the crop. Little information is available using whole crop barley as a buffer feed. The aim of these experiments was to evaluate the feeding value of whole crop barley (WCB) silage harvested at three stages of growth as a supplementary feed for grazing dairy cows during the late season.

Winter barley (var. Pipkin) was harvested at 4 stages of growth : T1:250, T2:350, T3:450 and T4:550 gDM/kg, at the following dates : 25/5, 19/6, 3/7 and 11/7/1991, respectively. The chopped material from T1-T4 was stored in minisilos and from T1-T3 in larger silos for animal studies.

Milk output has been manipulated by dietary methods for many years, however the underlying mechanisms for changes in milk composition are as yet unclear. In an attempt to further understand these mechanisms we have compared the mammary uptake of metabolites on two isoenergetic diets with different protein levels expected to provide different amounts of amino acid to the mammary gland.

Early- to mid-lactation Friesian cows were used to examine the effect of increased dietary protein supply on the supply of metabolites to and uptake by the mammary gland in relation to milk protein synthesis. Two barley based concentrates were formulated to contain 20.8 (Cl) or 29.1 (C2) g N/kg DM, using fishmeal (Provimi 66, high UDP) as the supplementary protein and fed with grass silage (28.3 g N/kg DM) at a total dry matter intake of 17 kg/day. In Experiment 1 these diets were fed at 50:50 (concentrate:silage) to four lactating cows fitted with rumen and duodenal cannulae in a simple crossover design.