Osteopontin, a glycoprotein, is expressed in several tissues including the mammary gland. The gene has been reported to be associated with milk and its constituents in various livestock species. This gene was sequenced in buffalo and it coded for the protein of 280 amino acids with the conserved GRGDS domain. The sequence was confirmed from the cDNA sequence derived from the mammary gland of buffalo. The earlier-reported 9T/10T variation in the upstream region of the gene was investigated for its effect on milk in buffalo and it was found to be non-significant.

This investigation was designed to evaluate the effects of the dietary inclusion of vegetable oil and its composition on fatty acid composition and lipid oxidation in pig muscle. Pigs were given the following diets from 50 kg to slaughter (90 kg): a control diet with no added fat (NF) or diets containing 20 g/kg of sunflower (SUN), olive (OL) or sunflower + linseed (SUN + LIN) oils. Meat from pigs given the SUN + LIN diet showed the highest thiobarbituric acid reactive substances (TBARS) from day 3 of refrigerated storage to the end of the experiment (P < 0·05). The OL group showed the lowest TBARS after 9 days of storage (P < 0·05). Pigs on NF showed intermediate values that were generally closer to those recorded for pigs given the SUN + LIN than the OL diet. By day 9, there was no statistical difference between the NF and the SUN + LIN group. The SUN group also showed intermediate TBARS throughout storage, with no statistical differences compared with the NF group. After 9 days of storage the lowest CIELAB a* value, corresponded to the SUN + LIN group and the highest to the OL group. These results indicate similar behaviour to that of lipid oxidation. Meat samples from pigs given the diet not enriched with fat showed greater drip loss than those given the remaining diets (P < 0·05) while there was no significant effect of dietary fat source on water-holding capacity. The inclusion of oils rich in linoleic fatty acids in pig diets modifies muscle fatty acid composition but susceptibility to lipid oxidation does not appear to be increased with respect to that occurring in pigs given diets with no added fat.

The object of this paper is to review some aspects of reproductive physiology in the pig, especially in relation to conditions after farrowing when reproductive ability is normally inhibited by lactation and suckling, and when weaning at different periods after parturition may have a profound influence on the chances of successful conception and pregnancy. In undertaking this review, however, it soon became clear that very few detailed experimental studies had been carried out in sows during the period immediately following parturition. It was considered best, therefore, to compare some of the situations which exist in pigs at other reproductive stages with what little is known about the sow at the post partum stage and during lactation.

Juke was expressed from two silages of contrasting fermentation type with either high (H) or low (L) levels of lactic acid and reconstituted either with the silage from which it had been expressed or the other silage. This procedure produced four dietary treatments (HH, HL, LL, LH) each differing in fermentation characteristics. The dietary treatments HH, HL, LL, and LH contained 81, 71, 59, and 49 g lactic acid per kg dry matter (DM) and 101, 133, 193 and 159 g ammonia-N per kg total nitrogen (TN) respectively. The four diets were offered to four steers (mean live weight 679 (s.e. 49) kg) in a four-period change-over design experiment. Each period was of 17 days duration. DM intakes were recorded daily, with intakes on days 8 to 17 used in the statistical analysis of data. On day 12 of each experimental period, rumen fluid samples were taken throughout a 24-h period. The rates of disappearance of DM, nitrogen (N), modified acid-detergent fibre (MADF) and neutral-detergent fibre (NDF) in the rumen were determined on days 14 to 17 using the polyester bag technique. DM intakes were 7·2, 6·9, 6·0 and 6·0 (s.e. 0·50) kg/day (P = 0·08) for HH, HL, LL and LH dietary treatments respectively. Diet had no significant effect on eating behaviour, rumen fermentation parameters or degradability of DM, N, MADF and NDF fractions (P > 0·05). Silage L increased rumen fluid pH (P < 0·05), reduced buffering capacity (P < 0·05) and increased the molar proportion of propionic acid and n-butyric acid (P < 0·05 and P < 0·01) compared with silage H. Silage L also had a lower DM apparent digestibility, D-value and DM, (P < 0·001), N and MADF (P < 0·05) degradabilities than silage H. The higher DM intake of dietary treatment HH compared with dietary treatments LL and LH could not be explained by any single constituent of the silages although it was apparent that physical characteristics of the silage were more important in determining intake than the chemical characteristics.

Litters that contained at least 13 mice were reduced at birth to 12, 8, or 4; and any natural litters of these sizes were also kept. The growth of these mice and their subsequent reproductive performance when mated at 6,10 and 14 weeks of age were recorded. All their offspring were weighed at weaning (4 weeks); some were weighed also at 12 days and 6 weeks of age.

The amount of milk supplied was not fully adjusted to the size of the litters. This had lasting effects so that, even at the oldest age for mating, the mice from the small litters were noticeably the heaviest. Litter size effects extended to significant differences in fertility (numbers born) and less obviously to the numbers weaned. The mice that were mated at 14 weeks were the most fertile. There was little to distinguish the mice from natural and reduced litters of the same size.

Small differences in weights of the offspring at 12 days, 4 weeks and 6 weeks of age bore no consistent relation to these factors.

Twenty bulls of three different breeds were tethered individually from 5 months until slaughter at 21 months. On the day of slaughter, the bulls were divided into groups of five animals, transported and then released in a pen. The first bull of the group was slaughtered 60 or 110 min after regrouping. Subsequent bulls were slaughtered individually at 50-min intervals. Social interactions among the bulls were recorded. Muscle pH, light reflectance values and water-holding capacity were measured in samples of m. longissimus dorsi. These characteristics showed correlations with the amount of non-agonistic social activity in which a bull had been involved before slaughter. The characteristics were also correlated with the number of agonistic interactions. Whether a bull was behaving as a dominant or a submissive animal did not influence the incidence of dark-cutting meat as judged by pH values. On the other hand, light reflectance values and water-holding capacity were correlated with the number of passive agonistic interactions (i.e. how many times a bull was attacked) and considerably less with the number of active interactions (number of attacks by the bull). The incidence of butting was not significantly related to muscle characteristics but mounting was significantly correlated with them.

The study indicates that dark-cutting beef is primarily caused by physically exhausting activities such as mounting, and further modified by stress-inducing social interactions.

Designs of open nucleus breeding schemes, which comprise a nucleus having the best males and females and a base comprising the remainder, with some base-born individuals used in the nucleus and vice versa, are studied.

Steady-state genetic responses, optimum transfer rates between nucleus and base in both sexes, and genetic differences between nucleus and base are estimated for a range of age structures, selection either within or among age groups (selection methods), nucleus sizes, mating ratios, fertility rates and survival rates appropriate to sheep and cattle populations. With optimum transfer rates between layers maximum or near maximum genetic responses are obtained with nucleus sizes varying from 2 to 15% of the population. Optimum transfer rates are fairly stable for nucleus sizes larger than about 5% and where the same selection procedures are used in both layers. However, a small nucleus with more efficient age structures and selection procedures and more accurate selection than in the base is economically desirable, and then almost no base-born females should be selected as nucleus replacements and up to 70% of male replacements for the base should come from the base. Optimum age structures differed markedly between selection methods.

Although few ‘rules of thumb’ about optimum age structures and transfer rates are sufficiently robust to be widely recommended in commercial situations, the nucleus breeding system behaves according to a few basic principles that can be used to predict the direction if not the magnitude of effects of changes in structure.

The suitability of a single mid-season targeted selective treatment (TST) for gastrointestinal nematodes control, based on flexible average daily weight gain (ADWG) thresholds, was investigated in 23 groups of first grazing season calves. In each group, animals were weighed three times: before turnout, at mid-season and at housing. Just after the first weighing, each group was divided in two homogenous sub-groups in terms of age, breed and weight, and randomly allocated to one of two sub-groups intented for two different mid-season anthelmintic treatment strategies: (1) a treatment of all calves composing the sub-group (whole-group treatment (WT)) or (2) a targeted selective weight gain-based treatment (TST) of the animals showing an individual pre-treatment ADWG inferior to the mean pre-treatment ADWG of the corresponding WT sub-group. Anthelmintic treatment (levamisole 7.5 mg/kg BW) was performed 3 to 4 months after turnout. At housing, two parasitological parameters (the anti-Ostertagia ostertagi antibody level-Ostertagia optical density ratio (ODR) and the pepsinogen level) and a clinical parameter (the breech soiling score) were assessed at individual level in each group. Then, the high exposed groups to gastrointestinal nematode (GIN) were defined as groups for which untreated animals exhibited a mean Ostertagia ODR ⩾0.7 and among these groups, the ones characterized by high abomasal damage due to Ostertagia for which untreated animals exhibited a mean pepsinogen level ⩾2.5 U Tyr were also identified. Among TST sub-groups, the treatment ADWG thresholds varied from 338 to 941 g/day and the percentage of treated animals from 28% to 75%. Pre- and post-treatment ADWG as well as parasitological and clinical parameters measured at housing were similar between TST and WT sub-groups including the 17 high exposed groups to GIN. Within these 17 groups, the treatment allowed to significantly improve post-treatment ADWG compared with untreated animals. In the six high exposed groups showing mean pepsinogen level ⩾2.5 U Tyr, the average effect of treatment on post-treatment ADWG was the highest and estimated up to 14 kg after a grazing duration of 4 months. In contrast, in six other groups showing mean Ostertagia ODR<0.7 in untreated animals, no effect of treatment was seen suggesting an absence of production losses related to a low level of GIN infection. This study highlighted the suitability of a convenient mid-season TST strategy for first grazing season calves, based on the use of flexible thresholds of ADWG, allowing similar growth compared with a whole-group treatment while keeping a GIN population in refugia.

When compared with other menadione derivatives such as menadione sodium bisulphite (MSB), menadione nicotinamide bisulphite (MNB), an organic salt combining menadione and nicotinamide, shows better stability towards physical and chemical factors once it is added to pre-mixes or foods. The present work evaluates the bioavailability of the two vitamins present in this compound and toxicity in the pig. To assess vitamin bioavailability, pigs were given small amounts of food containing MNB or equivalent amounts of MSB and nicotinamide in the free form. Menadione and nicotinamide concentrations in blood samples drawn at set times after the diets were given did not reveal any significant differences between the two modes of administration. Haematic levels of both vitamins in animals receiving MNB, or MSB and nicotinamide, were after 2, 4, 8 and 12 h higher (P < 0·001) than those of untreated animals. The tolerance level to MNB was evaluated in pigs given diets containing graded amounts of MNB (100, 500, 2500 mg/kg) for 28 days. No significant (P > 0·05) differences were recorded in live weight, food intake and gain/food ratio in pigs given these diets when compared with those given an unsupplemented diet. Haemoglobin and bilirubin levels did not differ between animals given various amounts of MNB and control animals. Plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in pigs given 100 mg/kg of MNB did not show significant differences when compared with those observed in pigs given an unsupplemented control diet. In pigs on the diets supplemented with 500 and 2500 mg/kg of MNB there was a significant increase in the two enzymatic activities as compared with controls (P < 0·001 and P < 0·01). In the case of ALT this had disappeared by 28 weeks. MNB is a good source of vitamin K for the pig and does not appear to have any adverse effects, even when administered at levels higher than those normally used in pig food supplementation.

The objective of this experiment was to replace soya bean oil with glycerol in laying hen diets and assess the change’s effect on performance, parameters of egg quality and the egg fatty acid profile. A total of 60 44-week-old Hy-Line W36 laying hens were distributed according to a completely randomised experimental design into four treatments consisting of glycerol substitutions for soya bean oil dietary at varying inclusion levels (0%, 25%, 50% and 75%), with five replicates of three birds each. Dietary treatments had no significant effect on BW change, egg production, feed intake, feed conversion ratio, egg weight and egg mass of laying hens. The inclusion of glycerol in the diet of laying hens had no significant effect on egg specific gravity, eggshell breaking strength, eggshell weight, eggshell thickness, egg shape index, albumen index, yolk index, haugh unit, albumen pH, yolk pH and egg yolk colour values. The inclusion of glycerol in the diet of laying hens had no significant effect on palmitic, palmitoleic, stearic, oleic and linolenic acid contents of the egg yolk. The linoleic acid and polyunsaturated fatty acid contents of the egg yolk significantly decreased with the higher levels of dietary glycerol supplementation (P<0.05). The results of this study show that it is possible to replace 75% of soya bean oil (4.5% in diet) with glycerol.

Quantifying robustness of farm animals is essential before it can be implemented in breeding and management strategies. A generic modelling and data analysis procedure was developed to quantify the feed intake response of growing pigs to perturbations in terms of resistance and resilience. The objective of this study was to apply this procedure to quantify these traits in 155 pigs from an experiment where they received diets with or without cereals contaminated with the mycotoxin deoxynivalenol (DON). The experimental pigs were divided equally in a control group and three DON-challenged groups. Pigs in each of the challenged groups received a diet contaminated with DON for 7 days early on (from 113 to 119 days of age), later on (from 134 to 140 days of age) or in both periods of the experiment. Results showed that the target feed intake trajectory of each pig could be estimated independently of the challenge. The procedure also estimated relatively accurately the times when DON was given to each challenged group. Results of the quantification of the feed intake response indicated that age and previous exposure to DON have an effect on the resilience capacity of the animals. The correlation between resistance and resilience traits was modest, indicating that these are different elements of robustness. The feed intake analysis procedure proved its capacity to detect and quantify the response of animals to perturbations, and the resulting response traits can potentially be used in breeding strategies.

Reproductive and production traits were studied in a crossbreeding experiment involving Red Danish cattle, Indian milch breeds and native Zebu cattle in various combinations.

Frequency of abortions and postnatal mortality were higher for Red Danish than for Indian milch breeds and crossbreds, age at first calving was higher for Indian milch breeds than for other groups, calving interval was longer for purebreds than for crossbreds. Milk and butterfat production in first and second lactation increased with increasing proportion of genes from Red Danish cattle. The range of milk production in first lactation was from 987 kg for Indian milch breeds to 3445 kg for Red Danish imported from Denmark.

The optimum proportion of genes from Red Danish for the environmental conditions prevailing in the present crossbreeding experiment is considered to be 60 to 80%.

The general aim of this research was to study the effect of high ambient temperature on the performance of does during lactation, specifically the following factors: average daily feed (ADFI) and water (ADWI) intakes, daily milk yield (DMY); milk composition: dry matter (DM), CP and gross energy (GE); doe BW (DW); individual kit weaning weight (IWW) and litter survival rate during lactation (SR). The study was undertaken comparing the performance of two groups of contemporary does reared under the same management, feeding regime and environmental conditions, except the environmental temperature and humidity. A total of 80 females were randomly allocated, at 60 days of age, into two identical and continuous rooms. In one room, the temperature was maintained permanently within the thermo-neutral zone (between 18°C to 22°C); thus, environmental conditions in this room were considered as comfort conditions. In the second room, the environmental temperature pattern simulated the daily temperature cycles that were characteristic of the summer in Mediterranean countries (24°C at 0800 h, increasing up to 29°C until 1100 h; maintenance at 29°C to 31°C for 4 h and decreasing to about 24°C to 26°C around 1700 h until 0800 h of the following day), which were considered as thermal stress conditions. Females followed a semi-intensive reproductive rhythm, first artificial insemination at 4.5 months of age, with subsequent 42-day reproductive cycles. Traits were recorded from a total of 138 lactations. Does were controlled up to the 5th lactation. Data were analyzed using linear and linear mixed models. High ambient temperature led to a lower ADFI (−9.4%), DW (−6.2%) and IWW (−8%), but it did not affect ADWI. No significant difference was found either for DMY, milk composition (DM, CP and GE) and SR during the lactation period. Heat stress was moderate, and does were able to adapt to it behaviorally by decreasing feed intake (to reduce heat production), but also live weight, allowing them to preserve milk yield and composition for assuring litter survival. On the other hand, water consumption could not be the main animal mechanism to overcome heat stress.

1. Three group feeding trials and two individual feeding experiments, involving a total of 202 pigs from 8 to 10 weeks of age to bacon weight, were conducted to determine the effect of processing (steaming, followed by rolling and grinding) of maize and barley on pig performance. The effect of supplementation of raw and processed cereal diets with two crude enzyme preparations was also studied.

2. Processing of maize or barley had no significant effects on rate of growth or efficiency of food utilisation in pigs fed on diets containing a proportion of bran and pollard, or of pigs fed on diets in which maize or barley constituted the entire cereal portion.

3. Neither enzyme preparation affected pig performance.

4. The growth rate and efficiency of food utilisation of pigs given diets high in maize were significantly better than for those given diets high in barley.

Cashmere production was evaluated on Scottish feral (F) goats, on goats imported from Iceland (I), Tasmania (T), New Zealand (N) and Siberia (S), and on two- and three-way crosses between feral and imported lines. Evaluations were based on the weight of cashmere in 10 cm2 mid-side patch samples taken at 5 months of age, with annual cashmere production being predicted from sample cashmere and body weights. Data were collected on 121 purebred and 706 crossbred kids of both sexes. Mean fibre diameter for the F, I, T, N and S lines was 13-75 (s.e. = 0.82), 14·04 (s.e. 0·41), 16·13 (s.e. 0·35), 16·63 (s.e. 0·49) and 17·97 (s.e. 0·50) μm, mean estimated annual cashmere production was 37·3 (s.e. 71·3), 914 (s.e. 31·7), 227·1 (s.e. 28·1), 275·1 (s.e. 42·5) and 579·8 (s.e. 44·7) g, and mean live weight was 15·71 (s.e. 2·16), 17·65 (s.e. 0·93), 16·39 (s.e. 0·83), 16·53 (s.e. 1·28) and 21·9 (s.e. 1·28) kg, respectively. Significant positive heterosis existed between some lines for body weight and cashmere production, with the I line goats consistently showing the largest effects. Combining fibre diameter and cashmere production by their relative economic importance into an index designed to indicate the total value of the fibre produced by each genotype, the cashmere production index, reduced the large production differences between the lines, although the S line was still superior to all other lines. When the cashmere production index was adjusted to account for the economic importance of fibre colour, however, the T and N lines, the only lines which produced white fibre, were comparable to the S line. The cashmere production index for the S line was very sensitive to changes in the relative economic weight for fibre diameter, and if the price differential for high quality (i.e. fine) fibre was increased by a factor of 1·36, or greater, then the T and N lines were superior to the S line. Three-way cross means were estimated from line means and heterosis effects. No cross was consistently superior to all other genotypes, but several of the crosses showed the advantages of potentially producing white fibre as well as having high cashmere production indexes, with their indexes being insensitive to changes in the relative economic weights. Future selection for cashmere production in this population should concentrate on individuals of outstanding genetic merit, regardless of their line or cross.

The specialization process associated with genetic selection could be associated with functional disorders, affecting the reproductive success of females (fitness). We hypothesized that by modulating energy acquisition and allocation of females we could balance productivity and reproductive success. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66) maternal line specialized in prolificacy, LP (n=67) generalist maternal line, R (n=70) paternal line specialized in growth rate. We fed each genetic type with two diets specifically designed to promote milk yield (AF) or body reserves recovery (CS). We controlled females between their first and fifth reproductive cycles, recording traits related with productivity and fitness of females. H females fed CS had on average 11.2±0.43 kits with an individual weight of 54±1.2 g at birth and 525±11 g at weaning. Their conception rate when multiparous was 44% and their survival rate at the end of the experiment 30%. When they were fed AF, the individual weight of kits was 3.8 g heavier (P<0.05) at birth and 38 g heavier at weaning (P<0.05), the conception rate when multiparous increased 23 percentage points (P<0.05) and the survival rate at the end of the experiment 25 percentage points (P<0.05). LP females fed CS had on average 10.8±0.43 kits with an individual weight of 52±1.2 g at birth and 578±11 g at weaning. Their conception rate when multiparous was 79% and their survival rate at the end of the experiment 75%. When they were fed AF, it only increased individual weight of kits at weaning (+39 g; P<0.05). R females fed CS had on average 8.4±0.43 kits with an individual weight of 60±1.2 g at birth and 568±11 g at weaning. Their conception rate when multiparous was 60% and their survival rate at the end of the experiment 37%. When they were fed AF, they presented 1.4 kits less at birth (P<0.05) but heavier at birth (+4.9 g; P<0.05) and at weaning (+37 g; P<0.05). Therefore, we observed that genetic types prioritized different fitness components and that diets could affected them. In this sense, seems that more specialized genetic types, were more sensitive to diets than the more generalist type.

Two experiments were carried out to evaluate extracted soya-bean meal, fish meal and maize gluten feed as protein supplements for calves offered grass silage ad libitum. The five treatments used in experiment 1 consisted of 1·4 kg per head daily of concentrate dry matter (DM) consisting of (g/kg) 50 molasses and 25 minerals and vitamins plus (1) 925 barley (B), (2) 700 B and 225 extracted soya-bean meal (SBM), (3) 785 B and 140 fish meal (FM), (4) 925 maize gluten feed (MGF) and (5) 2·25 kg DM per head daily of concentrate (1). Those used in experiment 2 consisted of 1·4 kg per head daily of concentrate DM consisting of (g/kg) (1) 1000 B, (2) 800 B and 200 SBM, (3) 860 B and 140 FM, (4) 1000 MGF and (5) 2·25 kg DM per head daily of B. In each experiment the diets were offered to 70 calves which were initially 131 and 130 kg live weight, for periods of 14 and 13 weeks in experiments 1 and 2 respectively. The silages contained 155 and 154 g crude protein (CP) per kg DM; 45 and 77 g ammonia-nitrogen per kg total nitrogen and 698 and 726 g digestible organic matter per kg DM in experiments 1 and 2. Concentrates 1 and 5 contained 104 to 110 g CP per kg DM and concentrates 2, 3 and 4 contained 195 to 204 g CP per kg DM in both experiments. For diets 1 to 5 respectively silage DM intakes were 2·31,2·50,2·53,2·59 and 1 -61 (s.e. 0·097) kg/day; live-weight gains were 0·84,0·98,1 -01, 0·88 and 0·95 (s.e. 0·032) kg/day in experiment 1 and 2·38, 2·53, 2·54, 2·82 and 1·77 (s.e. 0·045) kg/day and 0·90,1·04,1·03,1·05 and 0·99 (s.e. 0·038) kg/day for experiment 2. It is concluded that the use of soya-bean meal rather than fish meal did not affect silage intake or animal performance. Replacing mixtures of barley and soya-bean meal or barley and fish meal with an equal quantity of isonitrogenous maize gluten feed did not affect animal performance in one experiment but significantly reduced it in the other experiment.

Two experiments were performed to examine the efficacy of a synthetic prostaglandin analogue, cloprostenol (‘Planate’, ICI) to induce parturition in the rabbit. In experiment 1, does were injected intramuscularly on day 28 of pregnancy with either saline or with 4·38 μg, 8·75 μg, or 17·5 ug cloprostenol; a fifth group comprised untreated controls. Experiment 2 included only the groups treated with 4·38 μg and 17·5μg cloprostenol and untreated controls. In both experiments, cloprostenol injection significantly reduced the length of pregnancy when compared with saline-injected and untreated controls. Of the does treated with cloprostenol, 25 out of 26 kindled between 30 and 60 h after injection, whereas the variation in birth time in untreated and saline-treated groups was much greater (range 26 to 140 h). Litter birth weights tended to be lower in cloprostenol-treated does because of their precocious delivery but this did not appear to reduce pup viability. In both experiments, the proportion of pups dead at birth tended to be higher for does which did not receive cloprostenol (0·22 v. 0·10). Deaths between birth and weaning were similar on all treatments. Conception rate following mating 1 day after parturition appeared to be unaffected by cloprostenol treatment, as was milk yield during the 1st week of lactation.

A trial has been carried out to determine the effects of supplementing bacon pig diets with 125 and 250 ppm. copper (as copper sulphate) and/or aureomycin (14·4 ppm.). A total of 288 pigs were fed ad lib. from 40·100lb., and restricted-fed thereafter to bacon weight (200 1b.). Growth rate was increased by 125 ppm. copper, 250 ppm. copper, and aureomycin during the ad lib. feeding period. The magnitude of the responses was about the same in each case.

During the fattening stage from 100 1b. to bacon weight, 125 ppm. copper or aureomycin increased food conversion efficiency; 250 ppm. copper however improved growth rate also. There was probably some additive effect of 125 ppm. copper and aureomycin when fed together, but it is unlikely that such an effect occurred with the higher level of copper and aureomycin.

The liver copper content of pigs fed 125 ppm. copper was 3 times higher than that of the controls; 250 ppm. copper increased liver copper storage about 18·fold.

The similarity in response of copper and aureomycin feeding to pigs is discussed. It is concluded that, under the conditions of the trial, their mode of action is similar. Under similar conditions in general farm practice there is unlikely to be any economic advantage in supplementing pig diets containing 250 ppm copper with aureomycin; however, the bacterial environment may sometimes be such that additional benefit will be obtained by joint supplementation.

A two-pool model of tritiated water kinetics was investigated as a means of partitioning total body water into empty body water and gut water in 17 lactating goats. Empty body water, gut water and total body water were of a similar magnitude to, and highly correlated with, a rapidly equilibrating tritiated water pool, a more slowly equilibrating pool and the sum of these two pools, respectively.

Empty body fat was poorly correlated with both live weight and empty body weight (R2 = 0·42 and 0·51, respectively). However, there was a strong inverse relationship between the water and fat contents of the empty body. Consequently, empty body fat was accurately predicted by a multiple regression equation which included both empty body weight and empty body water as independent variables (R2 = 0·97). Substitution of these variables with estimates derived from tritiated water kinetics still resulted in a high correlation (R2 = 0·88). Tritiated water kinetics offered little improvement over live weight alone in the prediction of empty body protein, empty body ash or fat-free empty body.