Lameness is the greatest health and welfare concern in sheep flocks in the U. K. This thesis presents research on epidemiology of lameness in sheep Most previous studies quantifying lameness and its causes are based on the premise that farmers can identify the causes of lameness and recognise lame versus sound sheep. In 2005, a postal questionnaire was sent to a random sample of English sheep farmers to investigate whether farmers could correctly name six common foot lesions in sheep (interdigital dermatitis (ID), footrot (FR), contagious ovine digital dermatitis (CODD), shelly hoof, foot abscess and toe granuloma) from a characteristic picture and a written description. The same questionnaire of six lesions was presented at a meeting of specialist sheep advisors, primarily veterinarians. Approximately 20% of farmers and 80% of sheep specialists named all 6 lesions correctly, indicating a gap in knowledge between sheep advisors and sheep farmers. In addition, farmers tended to name any hoof horn damage as footrot which might imply that some lame sheep receive incorrect treatment. Management factors associated with the prevalence of farmer estimated lameness (irrespective of farmer recognition of lesions) and the adjusted prevalence of lameness caused by ID and FR among flocks where farmers correctly recognised both lesions were investigated and compared in negative binomial regression models. Farmers who routinely foot trimmed and frequently footbathed their sheep reported a higher prevalence of lameness, ID and FR. Farmers who stocked their sheep at >8ewes/hectare reported a high prevalence of both lameness and ID whilst those who separated `some' or `all' lame sheep at pasture reported a low prevalence of both lameness and ID. Farmers in the east of England reported a lower prevalence of lameness, ID and FR compared with central England. A numerical rating locomotion scoring scale (0-6) was developed to monitor locomotion in sheep in a research setting. There was good agreement between and within trained observers using this scale. This scoring system was used in a longitudinal study on one farm, two groups of sheep (30 in each group) with different treatment regimes (antibiotic injection & antibiotic spray vs. foot trimming and antibiotic spray; and occasional footbathing) for lameness with FR and ID were followed for five weeks to investigate the temporal associations between ID, FR and the effect of different treatments on locomotion. From the examinations it was concluded that even mildly lame sheep can have FR and ID. In a multilevel linear mixed model, there was a significant association between ID, FR and locomotion score with the mean score of 0.25 increasing to 0.43 for sheep with ID and to 2.18 for sheep with FR. In addition, sheep that developed FR had a significantly raised locomotion score the week before FR became clinically apparent. Treatment with antibiotic injection and antibiotic spray significantly reduced the locomotion score of sheep the following week. The movie clips from the locomotion scoring reliability study were used to investigate farmer and sheep specialist recognition of lame sheep and decisions on whether to catch them. A group of farmers from three regions (Devon, Newark and Norfolk) and sheep specialists at a Sheep Veterinary Society meeting were shown eight movie clips of sheep with varying locomotion scores. Although the majority of farmers and sheep specialists identified mildly lame sheep with a locomotion score of 2, only 50% of them would catch such a sheep if it was the only lame sheep in the group. Most farmers and sheep specialists did not catch lame sheep until the lameness was locomotion score 3 or 4. The more frequently farmers caught lame sheep, and the milder the lameness when a decision to catch was taken, the lower the farmer reported prevalence of lameness in the flock. The research in this thesis suggests that farmers, who are the primary carers for lame sheep, do not always name foot lesions correctly and so sheep may receive inappropriate treatment for some lesions. In addition, whilst farmers and sheep specialists can recognise lame sheep, they do not always catch and treat mildly lame sheep. Farmers who caught all mildly lame sheep within a few days of seeing them lame reported a lower prevalence of lameness in their flock. This might be explained by the evidence from this thesis that mildly lame sheep can have FR or ID and so prompt treatment of these lame sheep reduces the prevalence and incidence of FR and ID.

Four longitudinal studies were conducted. The first study investigated the longitudinal pattern of udder half somatic cell count (HSCC) and intramammary infection (IMI) in 48 UK suckler ewes over the first 10 weeks of lactation. This was the first study to demonstrate that HSCC of suckler ewes followed a quadratic and cubic relationship with days in lactation over the first 10 weeks of lactation. Udder half somatic cell count was also explained by presence of bacteria. Ewes older than 6 years of age had significantly higher HSCC than younger ewes. The second study investigated the relationships between udder conformation, SCC and lamb weight. Whilst accounting for lamb age and birth weight, significantly lower lamb weight was associated with a ewe SCC of >400,000 cells/ml (-1.7 kg), a traumatic teat lesion (bite, tear or chapping) 2 weeks previously (-1.1 kg), and a ewe body condition score (BCS) of <2.5 before lambing (-1.3kg). Higher HSCCs were observed in ewes with a lower suspended udder, and older ewes in poorer body condition. The findings from this study make an important contribution to the knowledge of the impact of udder health of suckler ewes by demonstrating that udder conformation is associated with IMI and that IMI and teat damage are negatively associated with lamb weight. The third study investigated the effect of dry cow therapy (DCT) on subclinical mastitis in a lowland flock with a low incidence of clinical mastitis by recording HSCC and lamb weights in the following lactation. To the author’s knowledge, there are no published reports of the effect of broad spectrum DCT on subclinical mastitis in suckler ewes in the literature. No significant effect was found between the use of DCT and HSCC or lamb weight in the subsequent lactation. The fourth study was a randomised controlled trial to assess the effect of DCT on clinical mastitis in a suckler flock with a high level of clinical mastitis. Dry cow treatment significantly reduced the incidence of clinical mastitis over one year, with a 70% reduction of clinical mastitis in ewes that received treatment from 6.2% to 1.8%. This was the first field trial to investigate and demonstrate the clinical benefit of the use of a broad spectrum DCT in suckler ewes. These studies have enhanced our knowledge of longitudinal patterns of infection and demonstrated the importance of udder health for optimising production of suckler ewes. Factors to control for when using SCC as a tool to measure intramammary infection were described.

A total of 450 isolates of Staphylococcus aureus were typed using multilocus sequence typing (MLST). They were isolated from the cattle and environment of a UK organic dairy farm, 43 dairy herds in the USA, the mammary glands of cattle in Chile and the UK, and also included the reference strain Newbould 305 (NCIMB 702892). Strains were compared to investigate differences between isolates from varying sites of isolation and the population detected on a single farm. MLST was suitable for the differentiation of bovine associated S. aureus, and thirty different sequence types were detected. These contained a number of novel alleles detected at each loci, agreeing with previous reports of host-specialisation, and indicating localised strain evolution. MLST was also able to discriminate between isolates detected in milk and on teat skin. The N ewbould 305 strain was significantly (p<0.05) associated with teat skin, and this may have important implications for future studies. The majority of isolates (87.4%) were present within one previously undescribed clonal complex (CC97), which contained representatives from all three geographic locations. Analysis of isolates from a single farrri demonstrated the clonality of the organism, supporting the theory of cow-to-cow spread of disease. No isolates were detected in heifer mammary secretions, suggesting transmission to these animals did not occur. Typing of multiple colonies from a single sample demonstrated strain heterogeneity within individual quarters. Environmental isolates were detected, though it is unlikely that they formed a significant reservoir of infection on the farm studied.

Automatic sampling and analysis of milk composition for on-line metabolic profiling has been proposed as a means of monitoring individual cows to detect and correct problems in nutritional management. Acetone, urea, fat, protein and citrate in milk were investigated independently and jointly as potential indicators for monitoring the dairy cow. A series of experiments and milk analysis were conducted to investigate sources of variation within and between cows, nutritional effects on milk composition and whether dietary changes could be detected through changes in milk composition. Novel methods for on-line acetone and urea analysis were also tested. Significant diurnal variation was found in fat, acetone and urea but not in citrate or protein. Acetone and citrate were the most variable constituents; day-to-day variation was 64.3% of mean acetone and 16.4% of mean citrate. Between cow variation was significant in all milk constituents monitored, in terms of means and normal concentration ranges, highlighting the need for individual cow management. Individual variation could be determined by establishing normal ranges of milk constituents for each cow, so that deviations from normal can be detected. Dietary changes at the group and individual cow levels were not detectable and individual responses to dietary changes were unpredictable. Changing the starch to fibre ratio in the diet had no effect on milk acetone and effects on urea, fat and protein were only significant when dietary changes were extreme. Energy output, in terms of FCM, was more closely correlated with fat: protein ratio (R2=0.3) than with acetone (R2=0.006), so the use of acetone as an indicator of metabolic status is inconclusive. Further research on a larger scale is needed to determine whether on-line monitoring will be feasible for nutritional management and economically justified in practice.

Despite the HACCP systems which have been introduced to the pork industry, cross-contamination which occurs within pork slaughterlines remains an important concern for food safety of the final carcass. The aim of this work was to understand the dissemination and cross-contamination of enteric bacteria during slaughter processing by investigating Escherichia coli populations. E. coli is widely used as an indicator of faecal or enteric pathogen contamination, and a strong correlation between the presence of Salmonella and E. coli levels was seen in this study. With microbiological counts and molecular typing of E. coli, changes of contamination levels as well as of the bacterial communities was observed during processing. The results demonstrated that temperature variation at different carcass sites during the singeing process allowed strains to survive on the cooler sites of the carcass and be present in the subsequent processing stages. The polishing process was recognised as an important site of cross-contamination not only because of an increase in contamination levels but also because a high variety of sources contributed contamination at this site, including strains surviving through singeing, strains that persist in the polisher overnight and strains from faecal leakage during the polishing process. A high percentage of virulence factor-carrying E. coli were present on the slaughtered carcasses and recombination between virulence genes from different pathovars was observed. These findings suggest carcasses slaughtered from a healthy pig herd may still be a potential source for E. coli pathovars in the food chain.

Maturational changes during the follicular phase of the porcine oestrous cycle were investigated in spontaneously cycling gilts. The results revealed considerable variation in the morphological and biochemical development of dominant follicles in the early follicular phase. This asynchrony was emphasised by the marked differences in follicular fluid steroid concentrations and LH binding to granulose cells and theca tissue between follicles of identical size within the same ovary. The nature of this variation may have great significance on our present understanding of asynchronies in embryo development. On the basis of the variables assessed in this study, those follicles destined to ovulate or to become atretic were only readily distinguishable on Day 20 of the oestrous cycle, suggesting that the selection of the preovulatory population continues over a 4 day period from about Day 16 to Day 20 of the cycle and, furthermore, that the selection process involves some initial maturation even in those unselected follicles that ultimately join the atretic pool. Leading on from this study, the control of the initiation of follicular development in lactating primiparous sows was examined by assessing the relationships between ovarian activity and circulating hormone levels following manipulation of the suckling stimulus. In the first experiment, piglet suckling behaviour and follicular development were 'investigated following a reduction in litter size to five piglets (split-weaning), seven days before weaning at 21 days post-partum. Overall, morphological and biochemical follicular development were significantly advanced (p < 0.001) in the treatment sows. The significantly (p < 0.001) greater concentration of follicular fluid oestradiol in follicles recovered from the split-weaned sows suggested that the supply of androgen substrate was probably limiting production of this steroid in the control animals. It was proposed that the latter was due to inadequate gonadotrophin stimulation. The comparative ethological study revealed that the remaining split-weaned piglets 'multiple-suckled' quarters vacated by their heavier litter mates. Despite a constant suckling frequency, suckling intensity was reduced in the split-weaned litters as evidenced by a regression in mammary tissue growth in the dams. In a subsequent experiment, further manipulation of the suckling stimulus was achieved by physically restricting the number of mammary quarters available to the piglets. Canvas sheeting strapped around the anterior quarters of one group of sows (cover) limited the five piglets remaining after split-weaning to suckle only the posterior quarters. An investigation of circulating hormone levels, 12 hours before and 48 hours after the start of treatment, revealed that, compared to the split-weaned and control sows, LH levels were significantly (p < 0.001) elevated in the cover sows with a concomitant significant (p < 0.001) depression in circulating prolactin. Although split-weaning induced a similar endocrine response in several sows, this effect was short-lived and overall, levels of both hormones were similar in the split-weaned group to those recorded in the control sows. The concentration of oxytocin, released at suckling was unaffected by litter size or the intensity of mammary stimulation. Ovarian activity at weaning was significantly enhanced in the cover (p < 0.001) and split-weaned (p < 0.001) groups. Hence, it was concluded that the critical factor influencing hormone levels and follicular development in the lactating sow was the neural intensity of the suckling stimulus. The cumulative data of the lactation experiments suggest that in practice, serious consideration should be given to the use of litter size reduction as a means of effectively improving the performance of the primiparous sow and her litter during lactation.

The importance of nutrition on reproductive performance is well recognised. However,the mechanisms and specific factors regulating their interaction are still poorly understood. Interest has recently intensified, as fertility in dairy cows has declined. There is a body of evidence on the negative effects of reduced body condition, the high levels of energy and protein intake, however, the results are inconsistent between studies and the role of specific factors, such as insulin and leptin, in the regulation of ovarian function in cattle remains unclear. The main objective of this thesis, therefore, was to test the effects of animal body composition, planes of nutrition and diet composition with emphasis on endocrine and metabolic factors, including progesterone, oestradiol, insulin, IGF-I and leptin, on oocyte quality and early embryo development in cattle. This thesis has demonstrated that alterations in planes of nutrition (Maintenance (M) vs twice maintenance (2M)) affected oocyte quality, and that the effects were dependent on animal body condition score (BCS) (Low vs Moderate). Whilst high (2M) levels of feeding were beneficial for oocytes from animals in Low BCS, they were detrimental to oocyte quality for animals in Moderate BCS. Furthermore, the combination of feeding level and animal BCS created low (10 ull.J/ml), moderate (20 ).lIU/ml) and high (40).lIU/ml) plasma insulin concentrations. Inevitably, however, it also led to the creation of three corresponding levels of plasma leptin concentrations (low: 2 ng/ ml, moderate: 4 ng/ml, and high: 7 ng/ml), indicating that the effects of these metabolic hormones on ovarian function cannot be separated in vivo. However, there was no correlation between changes in metabolic hormones and oocyte quality, suggesting that other endocrine or metabolic factors, not recorded in this study, may be involved in determining the post-fertilisation developmental competence of oocytes. Animal body composition also played an important role in the dietary-induced modifications to oocyte developmental competence both in vivo and in vitro. Indicated by post-fertilisation development in vitro, oocyte quality was enhanced in Low BCS heifers offered the Fibre than the Starch based diets (43.6 vs 24.6% blastocysts for Fibre vs Starch diet), whereas inclusion of protected lipid reduced oocyte developmental competence (27.7 vs 42.9% blastocysts for presence vs absence of Megalac). However, in Moderate BCS heifers, diet composition had litde effect on oocyte quality. Although dietary treatments had little effect on endocrine profile, elevated plasma leptin concentrations were consistently correlated (P<0.001) with increased animal body fatness. The effects of dietary treatments on oocyte maturation in vivo, however, varied from those observed when sera from these animals were used during the final stages of oocyte maturation in vitro, and during early embryo development. These findings suggest that while some diets may be beneficial to oocyte development, they could have a negative effect on embryo quality and subsequent survival. Interestingly, serum harvested from Low BCS heifers enhanced blastocyst formation in vitro compared to serum from heifers in Moderate BCS (24.2 vs 19.0%). This indicates that animal BCS is an important factor involved in the regulation of not only oocyte quality, but also early embryo development. The reasons for these discrepancies between BCS groups, however, remain unknown. Finally, this thesis produced an interesting and novel insight into the nutritional regulation of the lipid content and fatty acid composition of bovine plasma, granulose cells (GCs) and cumulus-oocyte complexes (COCs), and also the effects of serum from contrasting nutritional backgrounds on the lipid content and fatty acid composition of embryos. In general, the inclusion of supplemental fatty acids in the diet significantly increased the lipid content of all tissues tested. The fatty acid composition of COCs and embryos, however, was not correlated with their quality. Nevertheless, differences in the fatty acid composition of plasma, GCs and COCs indicated that there is a selective mechanism of fatty acid uptake by the follicle compartment, which has a preference for saturated fatty acids. The importance and function of specific fatty acids in determining oocyte and embryo quality remain to be elucidated. This thesis has therefore demonstrated that animal body composition is an important factor determining the effects of feeding level and diet composition on oocyte and early embryo development. In summary, high levels of feeding and the Fibre based diets can enhance oocyte quality in thin, but not in moderately fat animals. Alterations in plasma insulin and leptin concentrations did not appear to be correlated with oocyte quality in the present studies, indicating that other factors, not monitored in this project, are possibly involved in the regulation of oocyte developmental competence.

To overcome the `post-weaning growth check' commonly seen at weaning, the incorporation of antibiotic growth promoters (AGPs) to the diet has been a useful management tool. Recent legislation within the European Union banning the use of AGPs at sub-therapeutic levels in animal feed means that the quality of dietary ingredients used in weaner diets has assumed a much more fundamental role. In order to improve the availability of starch in the piglet diet, processing of cereals is widely practised. However, descriptions of processing techniques used in many studies are simply referred to by name, with no regard of the precise variables used. In addition, many of the feed materials are simply referred to as `cooked' which gives little indication of nutritional value. Five trials were conducted in order to assess the use of raw and processed cereals on diet component digestion, digesta properties and gut morphology in newly-weaned piglets. The main objective was to examine the use of precisely controlled processing variables, such that starch digestibility was maximised with benefits for the gastrointestinal environment. A second aspect of the programme of work reported was the application of a number of analytical tests commonly used in the field of human food science, to examine the physicochemical properties of starch granules, and the changes they undergo upon processing. Using this approach, a comparison could be made between in-vitro (rheological) results and in-vivo (biological) responses. Trials 1 and 2 examined variability between raw cereals. Wheat, barley, rye and triticale were assessed in Trial 1. Wheat (identical batch), naked oats, whole oats and maize were evaluated in Trial 2. Coefficients of apparent digestibility (CAD) for starch and nitrogen revealed considerable variation between the cereals. In Trial 1, there was a strong trend (P = 0.051) for starch digestion to be highest for the rye diet and lowest for triticale. CAD for starch was not significantly affected by cereal type in Trial 2. Despite having more viscous intestinal digesta than other animals (P = <0.001), pigs fed the rye-based diet did not experience any detrimental effects to animal performance. Trial 3 examined the use of raw wheat, of either hard or soft endosperm texture. From 5 days post-weaning, piglets fed the soft wheat diet had a tendency (P = 0.063) to have higher feed intakes. In addition, pigs fed soft wheat diets had significantly less viscous tract digesta (P = 0.029) than those animals fed the diet based on hard wheat. There was no significant difference in CAD for starch between the two dietary treatments but CAD for nitrogen was found to be significantly higher (P = 0.006) in the distal region of the small intestine for pigs fed the soft wheat diet. The results from Trial 3 suggest that endosperm texture of wheat can have an effect on nutritional value, and that wheat of soft endosperm texture is more beneficial than hard wheat for the young piglet. Trial 4 was a 2x2 factorial study examining wheat endosperm texture (hard vs. soft) and degree of micronisation (high cook vs. low cook). CAD for starch was not affected by endosperm texture, although degree of cook was an important factor with significantly higher starch digestion for the high cook diets, compared to low cook (P = 0.047). The use of micronised wheat lessened the reduction in starch digestibility seen on day 4 post-weaning in the small intestine, compared against the decline seen using raw wheat diets in Trial 3. In summary, Trial 4 demonstrated that micronisation can enhance the nutritional value of wheat for the weaned piglet, with degree of cook, a more significant factor than wheat endosperm texture. Trial 5 assessed wheat endosperm texture (hard vs. soft) and degree of extrusion (high cook vs. low cook). Raw soft wheat was used as a control. Results showed that CAD for starch in the small intestine was noticeably higher than in the other animal trials. Starch digestion was significantly affected by endosperm texture (greater coefficients for soft than hard; P <0.001) and by degree of cook (high SME greater than low SME; P <0.001). The use of extruded wheat diets almost eliminated the drop in starch digestion at the 0.5 intestinal site seen on day 4 post-weaning. Wheat of soft endosperm texture responded better to extrusion processing than hard wheat under the conditions of Trial 5. The use of computer modelling was able to demonstrate a correlation between in-vitro starch parameters and in-vivo starch digestion in the small intestine of the piglet.

Endoparasitic control is still heavily reliant on the use of anthelmintic drugs, however, frequent use and mis-use of anthelmintics is leading to the development of multiple resistance. In the tropics and subtropics where marginal levels of nutrition lead to greater susceptibility to infection, animal death due to nematode infection remains widely apparent. Here, anthelmintics are either unaffordable, of inferior quality or extensive multiple resistance has made these drugs ineffective. Consequently, alternative methods of parasitic control are required that are practical and realistic for introduction into farm production systems. One such possibility could be the exploitation of forage species capable of reducing parasitic infection solely, or in conjunction, with limited drug use. In tropical and subtropical regions many plants contain condensed tannins due to stress induced by environmental conditions. Sheep fed forages containing condensed tannins have been reported to have reduced gastrointestinal nematode infections. The aim of the studies reported in this thesis was to determine whether the inclusion of a model condensed tannin, quebracho tannin, and/or the elevation of dietary protein could reduce the establishment and persistence of small intestinal nematode infections. Initial work using the Nippostrongylus brasiliensis-rat model demonstrated that the inclusion of 40 g quebracho tannin/kg in both high and low protein diets significantly (p<0.05) reduced the number of N. brasiliensis establishing in the small intestine. Mean total daily faecal egg counts were also significantly (p<0.05) reduced by dietary quebracho tannin, and high dietary protein concentration. Data obtained from using the Trichostrongylus colubriformis-sheep model demonstrated that faecal egg counts were significantly (p<0.05) reduced when 50 g quebracho tannin/kg was included in a low protein diet. Increasing the dietary protein concentrations also reduced faecal egg counts to similar levels. The inclusion of quebracho tannin in a high protein diet did not significantly (p>0.2) reduce total daily faecal egg counts. Haematological and serological parameters did not show any significant (p>0.2) differences between dietary treatments. Subsequent investigations showed that dietary quebracho tannin was not reducing worm establishment and persistence by elevating the host immune response. Further studies suggested that quebracho tannin was acting through a direct toxic effect against the worm, where the mucosal inhabiting nematode, Trichinella spiralis, was unaffected by the presence of dietary quebracho tannin and in vitro data where N. brasiliensis survival was compromised by incubating worms in quebracho tannin-containing media. Concentrations as low as 0.01% (w/v) quebracho tannin proved effective at accelerating worm death. Thus, dietary quebracho tannin may be an alternative to increasing dietary protein concentration, which increases the hosts' capacity to mount an immune response and expel the worm burden from the small intestine. These data suggest that feeding condensed tannins may be a suitable alternative to anthelmintics, especially in the areas of the tropics and subtropics. However, the potential anthelmintic dietary properties of condensed tannins may be limited to parasites that are in direct contact with digesta and/or feed on intestinal contents, mucus and mucosal cells. Similarly, the diverse nature of condensed tannins may result with anthelmintic properties being restricted to a specific condensed tannin structure.

Tissue protein synthesis requires a simultaneous supply of energy and amino acids. The effect of altering diet and frequency of feeding on patterns of amino acid and acetate supply to peripheral tissues and the consequent effects on growth and carcass composition was investigated in growing lambs. A rumen 'asynchronous' diet with respect to the ratio of the rate of release of organic matter (OM) and nitrogen (N) was fed once daily (AD) or hourly (AR) and a more 'synchronous' diet was fed once daily (SD) to individually penned growing lambs (n=30) for 16 weeks. Plasma concentrations of acetate, amino acids and insulin were more constant throughout the day in animals fed AH compared to those fed AD. Those fed SD or AD had similar, large pulses in plasma acetate concentration following feeding. Animals fed AH had increased growth rates and greater amounts of carcass crude protein compared to those fed AD (P<O.OO1). Animals fed SD had faster growth rates with a higher amount of carcass crude protein and fat deposition than those fed AD (P>O.1). Synchronous diets formulated to have either slow (SS) or fast (FP) release of OM and N into the rumen were fed hourly (SSH or FFH) or once daily (SSD or FFD) to individually penned growing lambs (n=28) for 10 weeks. Plasma concentrations of acetate and insulin in groups fed once daily, increased after feeding, remaining elevated for longer in animals fed SSD. Amino acid concentrations decreased following feeding. Once daily fed animals tended to have greater amounts of crude protein in the carcass and generally heavier muscles than those fed hourly, particularly those fed SS. Animals fed AH had significantly higher feed intakes in the first experiment compared to those fed the diets once daily (P<O.OO1) which may be why these animals grew better and deposited more carcass protein than those fed once daily. It was thought that a pulse in acetate following feeding may contribute to an enhanced growth and carcass protein in ruminants. When sodium acetate was infused into growing lambs, intravenously, to raise the concentrations of plasma acetate similar to the pulse in acetate concentrations observed in the plasma of sheep following once daily feeding, no increase in whole-body protein synthesis was observed. The effect of temporal changes in the peripheral nutrient supply on protein synthesis in the ruminant requires further investigation.