A trial is described in which normal rations containing oleandomycin at 12½ and 25 g. per ton of meal and without the additive were given to females and castrates which had previously received creep feed with and without oxytetracycline.

A total of 48 pigs were individually fed on the rations from 50 to 200 lb. live-weight, a restricted scale of intake based on live-weight being adopted.

Between 50 and 100 lb. live-weight rate and efficiency of gain were significantly better in pigs which had not received antibiotic in the creep feed. No other treatment had any significant effect on performance.

Oleandomycin did not influence carcass measurements or dressing percentage. Minimum depth of fat at the mid-back was significantly greater in pigs which had received oxytetracycline in the creep feed while castrates had a significantly greater depth of fat at the shoulder and mid-back compared with females.

Pigs receiving the lower level of oleandomycin had significantly lighter kidneys than the control animals. Other visceral weights were not significantly influenced by the antibiotic, but females had significantly heavier kidneys, spleen and liver weights than castrates.

An investigation of milking ability in three dairy breeds has shown that selection for superior productive performance would contribute little to the improvement of milking time. The heritability of both average rate of flow and milking time was reasonably high in all three breeds, however, and direct selection should result in effective improvements.

The problem of slow milking was more acute in the Danish Red breed, in which almost one cow in ten needed more than six minutes to milk out, than in the Black Pied or Danish Jersey breeds.

A comparison of the average rate of flow and milking time as criteria of selection for milking ability indicated that both measures were equally effective in the Black Pied and Jersey breeds, but that rate of flow was considerably more (40%) effective than milking time in the Danish Reds. This was largely because the heritability of milking time in this breed was only one-third that of milking rate.

It was concluded that the average rate of flow was to be preferred to milking time as a criterion of selection for milking ability in the Danish station testing programme.

The relationship between puberty and the cessation of luteal activity after nutritional restriction was evaluated in 15 Angus × Hereford heifers. Heifers attained puberty at a body weight of 297 (s.e. 6) kg and a body condition score (BCS) of 5·5 (s.e. 0·1) on a scale of 1 (emaciated) to 9 (obese). After 154 (s.e. 16) days of nutritional restriction, heifers became anoestrus at a weight of 273 (s.e. 8) kg and a BCS of 3·0 (s.e. 0·2). The Spearman's rank correlation coefficient between date of-puberty and date of cessation of luteal activity was (r = –0·49; P < 0·06). This indicates that the heifers that attained puberty first were the last to cease luteal activity during nutritional restriction.

The effects of dietary sucrose, glucose and starch were compared to determine whether sucrose as an energy source affected energy or protein metabolism of growing pigs given food either frequently or once daily. Three experiments were conducted using three diets (0·8 g lysine per MJ digestible energy (DE)) containing sucrose, starch or glucose, respectively. In the first experiment, the DE contents of the diets were determined. In the second, the diets were given either once daily (08.00 h) or frequently (3-h intervals) to growing pigs (20 to 45 kg live weight) and growth responses, blood characteristics and energy, protein and fat retention measured. In the third experiment, the three diets were given to seven pigs (50 kg live weight), either once daily or frequently to monitor further the effects on plasma triglycerides, glucose, urea and insulin levels.

Growth rate, on a carcass basis, was slightly lower in pigs given glucose relative to starch (P < 0·05) but there was no effect of carbohydrate source on the retention of energy, protein or fat. Plasma triglyceride levels were lower in pigs given starch (P < 0·05) whilst plasma glucose and insulin concentrations were higher immediately after feeding in pigs given food once daily (7 < 0·05, P < 0·01). All three carbohydrate sources were used less efficiently by the pigs for energy, protein and fat deposition with once daily compared with frequent feeding (V < 0·01). Overall, these results indicate that sucrose as an energy source does not effect energy or protein metabolism by the growing pig. It appears that the metabolism of fructose within sucrose had no effect on metabolism.

The aim of this study was to compare responses to cold stress in newborn lambs and kids. Two experiments were conducted in a climatic chamber with controlled air temperatures and artificial wind and rain. The first experiment involved 25 Poll Dorset × (Border Leicester × Romney) lambs and 16 Angora × feral kids while the second involved 30 Suffolk × (Border Leicester × Romney) lambs and 26 Angora × feral kids. Rectal temperatures were measured and the rate of decline in rectal temperature estimated in both experiments. In the second experiment, metabolic rate was also measured and coat characteristics (birth coat depth and wool weight per unit area of skin) were examined. The effects of birth rank and sex on resistance to cold exposure and their interaction with species were examined in both experiments.

In experiment 1, kids had lower rectal temperatures than lambs at the start of the test but there was no species effect on the rate of decline in rectal temperature. In experiment 2, kids exhibited a significantly greater rate of decline in rectal temperature than did lambs. This difference in species effect between the experiments reflected primarily a greater rate of body cooling in the Poll Dorset-cross lambs (experiment 1) than in the Suffolk-cross lambs (experiment 2) rather than a difference between the kids in the two experiments. Additionally, in experiment 2, metabolic rate per unit live weight was significantly lower in the kids than in the lambs. No differences were apparent between the species in coat characters. Multiple-born lambs and kids were found to exhibit a significantly greater rate of decline in rectal temperature than singles, but only marginal differences in heat production were observed between the birth ranks. No significant effects of sex on resistance to cold stress were found in this study. Effects of birth rank and sex were additive with those of species. It is concluded that a combination of low heat production capacity and small body size is responsible for the generally poor responses of newborn kids to cold stress but there is probably little difference between lambs and kids in the insulative value of their birth coats.

1. Thirty lactating British Friesian heifers and cows were individually given maize silage ad libitum containing 331 g dry matter/kg, 13 g nitrogen and 11·2 MJ of metabolizable energy per kg dry matter. Urea or aqueous ammonia was mixed in at the time of feeding to give 7·0 g nitrogen per kg silage dry matter. Urea-treated silage was given with concentrates at a high (mean 6·6 kg dry matter/day: treatment HU) or a low (mean 3·3 kg:treatment LU) level of feeding; the lower level only was given with ammonia-treated silage (treatment LA).

2. The addition of ammonia raised silage pH values from 3·9 to 4·4. Silage dry-matter intakes in lactation weeks 7 to 22 for treatments HU, LU and LA were 8·8, 11·1 and 10·7 kg/day.

3. Digestible organic matter content in the dry matter of the diets measured in vivo was not significantly affected by treatment. However, digestible organic matter intakes were significantly greater for treatment HU than for LU in weeks 7 to 10, and for LU than for LA in weeks 11 to 22.

4. The yields of milk and the contents of protein, lactose and energy did not differ between treatments. The milk yields for treatments HU, LU and LA in weeks 7 to 22 were 20·2,19·2, 18·8 kg/day respectively. Fat content of milk was significantly depressed with the HU treatment for heifers in weeks 7 to 10. The live-weight changes of the cows in weeks 7 to 22 for treatments HU, LU and LA were +0·10, −0·07 and −0·37 kg/day; the live-weight loss by cows given treatment LA was significantly greater than for LU. The live-weight change of the heifers was not affected by treatment.

Measurements of longissimus dorsi pH at 45 min post mortem (pH1) were taken in 27 727 pig carcasses at four bacon factories. The overall least squares mean pH1 was 6·26 and 15·5% of carcasses had pHi values of 5·9 or less. Sex and commercial grade of carcass had little influence on muscle pHi or the incidence of values below pH 6·0. Factory differences were recorded in the distribution of muscle and within each there were marked producer effects in mean and the incidence of values below pH 6·0. Carcasses of Large Whites had fewer muscle pH1 values below 6·0 (12·4%) than those of British Landrace (18·7%), this being mainly due to a large breed effect at one factory. Although breed and testing background of sires of the carcasses examined and the first order interactions with factory had significant effects on muscle pHi and the incidence of values below pH 6·0, they were of little practical significance.

Forage crops of the genus Brassica are known to contain goitrogens which under certain conditions can cause severe incidences of neonatal mortality in lambs and goitre in older sheep (Shand, 1952; Sinclair and Andrews, 1958, 1959, 1961; Andrews and Sinclair, 1962).

In the course of studies of certain aspects of lamb growth it was noted that lambs grazing rape (Brassica napus) had heavier thyroid glands than comparable lambs grazing grass. Pipes, Premachandra and Turner (1958) found that a degree of hypothyroidism increased the rate of fattening and influenced the carcass quality of cattle, and in view of this and other evidence it was decided to test the hypothesis that changes in the weight of the thyroid glands of lambs grazing rape were associated with changes in the rate of live-weight gain.

The optimum pattern and limiting order of some essential amino acids for growing-furring blue foxes were assessed from nitrogen (N) retention responses. Total tract digestibility and N balance trials were carried out on 24 weaned blue fox males in an 8 ✕ 5 cyclic change-over experiment. Eight experimental diets were prepared by removing proportionately about 0·4 of each of the amino acids studied – methionine + cystine, lysine, threonine, tryptophan and histidine – successively from the amino acid control diet. The main source of protein in the amino acid control diet was casein and an amino acid mixture was added to bring the calculated crude protein (CP) content up to the level of 170 g/kg dry matter (DM). Low-protein (CP 95·7 g/kg DM) and high-protein (CP 166·6 g/kg DM) diets, the protein proportion of which was casein protein, served as negative and positive control diets, respectively. The reduction in N retention when one amino acid in turn was deleted from the amino acid control diet was calculated, and a regression analysis was made between N retention and relative amino acid intake. Data on the animals’ intake of each limiting amino acid and those on the amino acid control diet were used. The optimum amino acid pattern, expressed relative to lysine = 100, proved to be: methionine + cystine 77, threonine 64, histidine 55 and tryptophan 22. The first-limiting amino acids were methionine + cystine. Blue fox responses (N retention, weight gain) to deletion of methionine + cystine from the diet were very severe and exceeded those to deletion of any other amino acid. Moreover, removing methionine + cystine from the diet significantly impaired the apparent digestibility of organic matter, reducing it to a level even lower than that of the low-protein diet. After methionine + cystine, the next-limiting amino acid in casein-based diets was threonine, followed by histidine and tryptophan. The results show the importance of verifying the sufficiency of dietary methionine + cystine in the practical feeding of blue foxes.

Haemoglobin and potassium types were related to body weights from birth to 1 year of age and first 6-monthly wool yield in the Nali breed of Indian sheep. Weighted mean comparisons between haemoglobin and potassium types made within sires for weights at birth, weaning (3 months), 6 months and 1 year and first 6-monthly wool yield did not show any statistically significant differences for any of these traits.

A theoretical equation is proposed which describes the dynamics of foetal growth in mice. The equation is basically of exponential form and takes into account the effects of stage of gestation (T) and number of foetuses (N) on the instantaneous relative growth rate. The model was tested against experimental data by using a stepwise regression technique. Both stage of gestation and number of foetuses had significant effects (P < 0·01) on the instantaneous growth rate. When the model was tested against another set of data 44 out of a total of 52 comparisons had a prediction error less than 15 %. As a result, the following equation is proposed to describe the foetal growth of mice

W = e-14·34Ne(1·302–0·0276T–0·00059)T

An equation of this form could be useful in interpreting prenatal growth data for other species. Other factors which may influence the dynamics of foetal growth, such as maternal age or weight, could also be incorporated into the equation.

Four experiments were carried out with calves offered pellets containing different ratios of cereal/protein concentrate and dried grass together with 10% chopped hay. Organic matter digestibility of total ration declined by 5·2 percentage units for each 25% increment of dried grass.

Dry matter (DM) intake of the total ration increased as dried grass content increased from 0 to 50% which led to similar intakes of digestible organic matter (DOM) and daily gain. When pellets contained 75% dried grass, total DM intakes were reduced in two experiments, leading to DOM intakes and daily gains similar to that of calves offered pellets of dried grass only. In the third experiment, DM intake of pellets containing 75 % dried grass was greater than the intake of pellets containing 50 to 100 % dried grass. When equal quantities of DM were offered, DOM intakes and daily gains tended to decline linearly as dried grass content in the pellet increased. The replacement value of the dried grass for concentrate at equal levels of live-weight gain was 1·36: 1.

The relationship was examined between the composition of carcasses from 30 castrated Hereford male cattle and their profile areas obtained from photographic negatives. The accuracy of this method n i determining fatness was compared with that of other methods including visual assessment.

Photographs were taken of a dorsal view of the intact carcass and lateral and medial views of the left side after splitting the carcass. A planimeter was used to measure the areas which were obtained from photographic negatives. Carcass lengths were recorded from the medial views. A panel of six judges assessed the sides for fatness on a seven-point scale with the aid of photographic standards.

Areas and carcass lengths, adjusted to dimensional parity, were used as independent variables in multiple regression analyses, with the weights of the dissected tissues as dependent variables. Explanation of variation in muscle weight was poor, but dorsal area and length were (very nearly) as good as visual score and side weight in predicting total fat weight.

Five diets of identical metabolizable energy (ME) content were formulated, in which wheat silage, made from a variety bred for a high proportion of ears to roughage, was incorporated at the rate of 480 g/kg dry matter (DM). Their calculated ME density was 11-4 MJ/kg DM, the protein concentration of four of the five diets was 150 g/kg DM, and that of the fifth was 87 g/kg DM. The effectiveness of protein supplementation of such diets by non-protein nitrogen (NPN), fish meal (FM) or soya-bean and cottonseed oil meals (SBM and CSM) was studied in a digestibility and nitrogen balance trial, and in a feeding trial using Friesian and beef breed young bulls. One diet served as a negative control (NC). The apparent digestibility of organic matter (kg/kg DM) was 0·709, 0·708, 0·704, 0·680 and 0·667 (s.e. 0·0125) and nitrogen retention (g/kg M0·75 per day) was 0·20, 0·65, 0·65, 0·64 and 0·68 (s.e. 0·059; P < 0·01) for the NC, NPN, FM, CSM and SBM supplemented diets, respectively. The feeding trial was divided into two periods; the first 100 days, and from day 101 to slaughter. The NC groups of both breeds gained significantly less in both periods of the experiment than did the supplemented groups. There were no significant differences among the supplemented groups.

Hyaluronic acid (HA) is a polysaccharide preferably extracted from cockerel combs and used for medical purposes, mainly eye surgery. One way of increasing the production of HA from cockerels is to increase the size of the combs. The aim of this work was to study comb development and quantify direct and correlated responses for comb size at different ages and comb weight in two lines of White Leghorn selected for comb size at two different ages. Two lines were created, one selected for comb size at 16 weeks of age (CS16) (line E = early comb development) and the other for comb size at 29 weeks of age (CS29) (line A = adult comb size). There were between 500 and 800 birds of each line and generation and the lines had been selected for five generations. Cockerels in line E developed the combs at an earlier age and had smaller 29-week combs compared with the cockerels in line A. Genetic gain for the selection trait in generation five, measured in relation to line means in generation 1, was 58% in line E and 36% in line A. The corresponding correlated response for CS29 and comb weight (CW) in line E was 28% and 25% respectively, while for CS16 and CW in line A it was 46% and 35%. The results indicated that it is possible to increase cockerel comb size at both 16 and 29 weeks of age through selection.

An experiment was carried out over successive years (1982 and 1983) to measure the extent to which live-weight advantage as a result of feeding in the dry season was maintained during the subsequent wet season at pasture. Two ages of Brahman steer (weaners and yearlings) were kept on three dry season treatments (molasses, sugar cane or grazing only) from January to May and then turned out to pasture as a single group until November. Although the molasses and sugar cane treatments produced significantly higher live-weight gains during the dry season the resultant weight advantage at turn-out was largely reduced during the wet season due to compensatory growth exhibited by previously restricted animals. Yearlings were less able to compensate than weaners.

The voluntary intake and apparent digestibility of kleingrass (Panicum coloratum cv. Verde) were measured in seven periods, comprising one full year. The forage was offered twice a day ad libitum to seven rams, fitted with faeces collection bags; each experimental period was composed of 8 days for adaptation and 8 days for collection of data. The dry-matter (DM) intake (DMI) varied from 36·1 to 64·9 glkg M075, the digestible dry-matter intake (DDMI), from 17·4 to 41·9 glkg M0·75 and the in vivo dry matter apparent digestibility (DMD), from 0·471 to 0·667.

Daily samples of offered forage were taken and pooled subsamples from each of the seven periods were incubated in nylon bags in the rumen of three Hereford steers. The data were fitted to the exponential equation: p = a + b (1-e-ct) to estimate p (the proportionate loss of DM at time t of incubation); effective degradability (ED) and lag time (L) were also estimated.

The parameters obtained in situ were related to the in vivo results by simple and multiple regression. The correlation coefficients of the rate of degradation (c) and ED with DMI, DDMI and DMD were, respectively, 096 and 0·97; 0·97 and 0·96; 0·86 and 0·88. By including a, b, c and L into a multiple regression analysis, the coefficients of determination (R2) were: DMI: 0·99; DDMI: 0·99 and DMD: 0·91. Within the conditions of this study, the parameters obtained in situ were reasonable estimators of voluntary intake and apparent digestibility.

A total of 52 ram lambs of different morphological types slaughtered at a comparable stage of body development (carcass weights = 19·5 (s.d. 3·10) kg) were used to study the variation in the relationship between muscle and bone development in the hind limb using multivariate techniques. Development of individual muscles was expressed relative to the weight of the major bone to which they are closest, considered here as their carrier bone.

Variability of muscle: bone ratios of individual muscles varied considerably from one muscle to another. The coefficient of variation (CV) ranging from 0·111 to 0·462 (average CV = 0·199). Relative to the same bone, the variability of muscle: bone ratios for each of the three anatomical regions of the hind limb was still important. This suggests that variability may be due to other factors besides muscle weight, such as bone shape.

The correlation between the various muscle: bone ratios was low in some cases. However, a significant association existed between muscle: bone ratios of individual muscles and the total muscle: bone ratio in the hind limb which indicated that some muscle: bone ratios can be used as indicators of muscling in the selection of meat animals such as m. semimembranosus/femm, m. gluteobiceps/femur, m. adductores/'femur and m. semitendinosus/femur.

The most discriminant variables of the population in multivariate analysis were m. soleus/tibia, m. extensor digitorium lateralis/tibia, m. quadmtus femoris/coxal, m. gemelli/coxal and m. vastus medialis/femur. It was also possible to distinguish the different morphological types of the different breeds by the values of the ratios between these variables.

Over the past decade, in vitro methods have been developed to study intestinal fermentation in pigs and its influence on the digestive physiology and health. In these methods, ingredients are fermented by a bacterial inoculum diluted in a mineral buffer solution. Generally, a reducing agent such as Na2S or cysteine-HCl generates the required anaerobic environment by releasing metabolites similar to those produced when protein is fermented, possibly inducing a dysbiosis. An experiment was conducted to study the impact of two reducing agents on results yielded by such in vitro fermentation models. Protein (soybean proteins, casein) and carbohydrate (potato starch, cellulose) ingredients were fermented in vitro by bacteria isolated from fresh feces obtained from three sows in three carbonate-based incubation media differing in reducing agent: (i) Na2S, (ii) cysteine-HCl and (iii) control with a mere saturation with CO2 and devoid of reducing agent. The gas production during fermentation was recorded over 72 h. Short-chain fatty acids (SCFA) production after 24 and 72 h and microbial composition of the fermentation broth after 24 h were compared between ingredients and between reducing agents. The fermentation residues after 24 h were also evaluated in terms of cytotoxicity using Caco-2 cell monolayers. Results showed that the effect of the ingredient induced higher differences than the reducing agent. Among the latter, cysteine-HCl induced the strongest differences compared with the control, whereas Na2S was similar to the control for most parameters. For all ingredients, final gas produced per g of substrate was similar (P>0.10) for the three reducing agents whereas the maximum rate of gas production (Rmax) was reduced (P<0.05) when carbohydrate ingredients were fermented with cysteine-HCl in comparison to Na2S and the control. For all ingredients, total SCFA production was similar (P>0.10) after 24 h of fermentation with Na2S and in the control without reducing agent. Molar ratios of branched chain-fatty acids were higher (P<0.05) for protein (36.5% and 9.7% for casein and soybean proteins, respectively) than for carbohydrate (<4%) ingredients. Only fermentation residues of casein showed a possible cytotoxic effect regardless of the reducing agent (P<0.05). Concerning the microbial composition of the fermentation broth, most significant differences in phyla and in genera ascribable to the reducing agent were found with potato starch and casein. In conclusion, saturating the incubation media with CO2 seems sufficient to generate a suitable anaerobic environment for intestinal microbes and the use of a reducing agent can be omitted.

Determining best practices for managing free farrowing systems is crucial for uptake. Cross-fostering, the exchange of piglets between litters, is routinely performed amongst crate-housed sows. However, cross-fostering can increase fighting amongst the litter and may be more challenging within free farrowing systems as sows have more freedom to respond to cross-fostered piglets. This study compared the effect of either cross-fostering (FOS), or a control of sham-fostering (CON), of four focal piglets per litter on Day 6 postpartum in crates (CRATE) and free farrowing pens (PEN). The post-treatment behavioural responses of sows were recorded (Day 6 = 60 min; Day 7 = 300 min; n = 48), as were the average daily gain (ADG; g/day), total weight gain (TWG; kg) and body lesion scores of focal piglets and their littermates throughout lactation (Day 6, Day 8, Day 11 and Day 26; n = 539) and the post-weaning period (Day 29, Day 32 and Day 60; n = 108). On Day 6, though post-reunion latency to nursing did not differ, latency to successful nursing was longer amongst FOS than CON litters (P < 0.001), more so amongst CRATE FOS than PEN FOS (P < 0.01). On Day 7, PEN FOS sows had fewer successful nursing bouts (P < 0.05) and exhibited decreased lateral (P < 0.01) and increased ventral lying frequencies (P < 0.01) compared to all other housing and treatment combinations. Focal piglet ADG was lower for FOS than CON in the CRATE during Day 6 to Day 8 (P < 0.01) and lower in the PEN during Day 6 to Day 8 (P < 0.001), Day 8 to Day 11 (P < 0.01) and Day 11 to Day 26 (P < 0.05). The TWG of pre-weaned focal piglets (Day 6 to Day 26) was higher amongst CON than FOS litters (P = 0.01). Post-weaning, piglet ADG was higher for PEN than CRATE during Day 26 to Day 29 (P < 0.01) and higher for FOS than CON during Day 26 to Day 29 (P < 0.05), Day 29 to Day 32 (P < 0.001) and Day 32 to Day 60 (P < 0.01); thus, TWG was higher for FOS than CON during the weaner (P = 0.001) and the combined lactation and weaner periods (P = 0.09). In conclusion, sow behaviour was disrupted by cross-fostering in the crates and pens and continued to be disturbed on the following day amongst penned sows. FOS piglets exhibited reduced ADG after cross-fostering, which extended throughout lactation in the pens. However, the increased post-weaning weight gain of FOS piglets meant that their TWG was higher than CON piglets, irrespective of the farrowing system used.