For centuries, animal breeders have very effectively been selecting livestock species, making use of the natural variation that exists within the population. As part of the developments towards broader breeding goals, the RobustMilk project was designed to develop new practical technologies to allow breeders to re-focus their selection to include milk quality and dairy cow robustness and to evaluate the consequences of selection for these traits taking cognisance of various milk production systems. Here we introduce the background to robustness, the value of expanding milk quality analysis (including the possibility of using milk quality characteristics as proxy measures for robustness traits), interactions between robustness and milk quality traits and the need for different breeding tools to enable delivery of these concepts to the industry. Developing a database with phenotypes from research herds across Europe, phenotyping tools using mid-infrared red spectroscopic analysis of milk, and the development of statistical and genomic tools for robustness and milk quality formed the core of the project. In the following papers you will read the outcomes and developments that happened during the project.

In the spring of 1932 an experiment was set up to observe the effects of intensive grazing, by the heavy stocking of a pasture, on the worm infestation of animals, and to arrive at some estimation of the consequences of modern grazing practices. These observations covered a period of one year and the results obtained from the experiment, which was carried out by one of us, have been put forward in an earlier paper (Morgan, 1933). Some conclusions were drawn from the work but these were considered as purely provisional owing to the small scale of the experiment and to the observations covering the comparatively short period of a year. It was pointed out that the effects of overstocking would not become evident until pastures had been under a system of rotational grazing for many seasons and when the concentration of helminth ova and larvae had reached a very high level. With this in mind it was decided to proceed with observations on the effects of heavy stocking on the worm burden by setting up a fresh experiment running on lines similar to that already described but using, in places of the goats in the 1932–33 work, one-year old sheep, as it was thought that this type of stock would ensure a closer cropping on the experimental plots.

The question of helminth parasitism in British goats appears to have had little or no attention paid to it. This is somewhat surprising when one considers the fairly large number of goats which must be present in this country and, although no annual statistics as to the number of goats in Britain are available, Holmes Pegler (1929) observes that early in 1925 the Ministry of Agriculture, assisted by the British Goat Society, obtained returns of the number of goats in England and Wales which was set down as, roughly, 60,000. Similarly little definite data is available on the frequency and intensity with which these animals are infected by helminths in different localities. In this paper an attempt is made to supplement the meagre data relative to these conditions.

Three double-marker systems were used in cannulated steers offered straw-based diets supplemented with barley, fishmeal or a combination of both, in an attempt to reduce the risks of misinterpreting biological results based on calculations of digesta flows using markers. Ruthenium phenanthroline (Ru-phe), ytterbium acetate (Yb-ac) and the indigestible acid detergent fibre fraction (IADF) were used as markers of the particulate phase of digesta in conjunction with Cr-EDTA as a liquid-phase marker to estimate duodenal and ileal digesta flows. The present paper presents the difficulties met in the application of marker techniques.

The particulate marker used in a double-marker system for calculation of nutrient flow modified the degree of statistical significance observed for dietary treatment effects on digesta flow parameters.

The data suggest that the type of diet used affects the behaviour of individual markers in different ways and could incur some bias in the results. It is hypothesized that the physical and chemical characteristics of digesta, in different dietary conditions, can be responsible for differential attachment of markers to particles of the solid phase. In such cases, the distinction made in the double-marker technique between particulate and liquid phases may not be sufficient to correct for lack of representativeness of digesta contents sampled from T-shaped cannulae.

For the diets studied it was concluded that the interpretation of digestion parameters should be based on both Ru-phe and Yb-ac results.

Vascular injection or infusion of isotopically labelled fatty acids into both ruminant and nonruminant species has been used as a method for determining the entry rate of non-esterified fatty acids (NEFA) into blood (Bickerstaffe, Annison & Linzell, 1974; Vranic, 1975). Results obtained in this way represent the release of fatty acids from several sources, principally adipose tissue. The predominant labelled end-products from [3H]– and [14C]fatty acid metabolism are water and carbon dioxide respectively. Both these metabolites enter extensive body pools and the label is unlikely to be reincorporated into plasma NEFA during the time course of conventional short-term experiments (2–4 h). During isotope dilution experiments, however, some labelled fatty acid could be incorporated into adipose tissue triacyglycerol (TAG) following synthesis of low-density lipoprotein in the liver. In addition, the contribution of NEFA carbon to endogenous acetate production could result in transfer of 14C in any C, or 8H attached to the C8 position in acetate, from the infused fatty acid to fatty acids synthesized by liver and adipose tissue.

A number of attempts have been made, notably by workers in Australia (Nolan, 1975; Pilgrim et al. 1970) and Canada (Mathison & Milligan, 1971; Kennedy & Milligan, 1978a, b) to trace the metabolism of rumen ammonia-N in sheep.

Rumen fermentation, duodenal digesta flow and N balance were studied in three sheep fed diets which contained urea or fishmeal as nitrogen supplement and either barley straw, barley + corn starch or molassed wheat straw (60% molasses) as carbo-hydrate source.

The molar composition of rumen volatile fatty acids (VFA) with straw diets was high in acetate (64–68%), with barley diets high in propionate (32–36%) and with molasses diets high in butyrate (28–34%). Rumen ammonia concentrations (RAC) were low and constant with fishmeal diets (< 10 mM) but varied with carbohydrate source with urea diets. RAC was very high (24 mM) after feeding molasses + urea.

With barley and molasses diets 73–75% of digestible dry matter (DDM) was digested in the stomach, but only 54–59% with ground and pelleted straw diets. For all diets less N passed the duodenum than was eaten. The lowest daily duodenal N passage was with molasses + urea. Daily urinary N output was highest (P < 0·01) for this diet and nitrogen balance lowest.

Daily intakes of amino acids differed widely between diets but differences in duodenal passage were not so great. Molasses + urea provided the lowest values for daily duodenal amino acid flow. The amino acid content of duodenal N (mM amino acid/16 g N) was relatively constant despite broad variation between diets. Digesta alanine and valine (mM/16 g N) were higher for barley than for straw diets (P < 0·05). Digesta methionine (mM/16 g N) was lower for fishmeal than for urea diets (P < 0·01).

Very little sucrose reached the duodenum with any diet.

It was concluded that the form of energy-yielding nutrient inuflenced duodenal N flow by affecting ammonia-N capture in the rumen, but that the amino acid content of duodenal N was little affected. The interaction between molasses and urea was not beneficial to efficient use of urea-N in this work when molasses was the major carbohydrate component of the diet.

The aim of this work was to test the robustness of the 0.68 estimate of the efficiency of conversion of metabolisable protein into true milk protein (Agriculture and Food Research Council (AFRC), 1993) for protein-limiting diets and to determine whether a different value is appropriate for practical rationing. Seventy-two multiparous cows were blocked on the basis of milk energy output per unit of dry matter intake (DMI), and allocated at random to one of four treatments. Treatments supplied metabolisable energy (ME) at a fixed level to individuals within a block, but varied metabolisable protein (MP) supply from 25% below the estimated requirements, through −12.5% and +12.5% up to 25% above requirements for the average performance of animals within blocks at the start of the study. Cows were offered diets to meet their predicted ME requirements for each 3-week period with measurements performed in the last week of each period. Milk protein output was regressed against the estimated MP available for production for each cow and the efficiency of conversion of MP into milk true protein was calculated, assuming a maintenance requirement according to the MP system. The efficiency of conversion of MP into milk true protein decreased with the increasing supply of MP from 0.77 to 0.50. Using an iterative approach to determine the best fit of the data when supply matched requirement resulted in a range of efficiency values between 0.62 and 0.64 g of true milk protein per g of MP.

With the aim of testing the effects of food quality on meal patterns 127 213 visits by 22 lactating cows to 12 computerized feeders supplying two foods, high forage (HF) and high concentrate (HC) consisting of grass silage and concentrate were analysed. The foods were composed of the same ingredients but the proportion of concentrate dry matter (DM) in the food DM differed between HC (0·59) and HF (0·27). Each of the foods was offered ad libitum to 11 cows from the start of lactation until 156 (s.e. 9) days after calving. Mean daily fresh food intake (49·2 kg) was not affected by treatment. Mean daily intake of DM differed between HC (23·6 kg) and HF (17·8 kg). After estimating individual meal criteria, visits were grouped into meals. The mean daily number of meals was 6·6, the mean fresh food intake per meal was 7·6 kg and neither was affected by treatment. Cows consuming HF had longer meals (41·4 v. 31·3 min) but a lower feeding rate than cows consuming HC (233 v. 337 g of fresh food per min and 78 v. 156 g DM per min). Pre- and post-prandial correlation coefficients were sometimes statistically significant but always low (R2 from 0 to 0·05) and not affected by treatment. Food intake per hour of the feeding cycle (defined as the intake during a meal divided by length of the meal plus the duration of the preceding between-meal interval) showed a diurnal pattern in the shape of a sine-wave with low values of about 1·5 kg/h for cycles starting just after midnight and high values of more than 3·0 kg/h for cycles starting just after noon. Neither the mean, nor the amplitude, nor the shift of the sine-wave were affected by treatment. The data suggest that similar mechanisms are responsible for the short-term intake regulation of HC and HF. No evidence was found to suggest that the diurnal meal pattern of cows consuming HF deviated from that of cows consuming HC as a result of differences between foods in constraints related to their physical properties.

Prolonged periods of stress have been associated with impaired immune function; the experiment reported here investigates a potential link between level of metabolic load and immune function in lactating dairy cattle. A group of 111 Holstein-Friesian dairy cows was used. The cows belonged to one of two genetic lines: a selection line (S) with high genetic merit for fat plus protein yield and an unselected control line (C). The cows were offered one of two silage-based total mixed diets containing either 200 g (LC) or 450 g (HC) of concentrate per kg dry matter. Combination of genetic selection and food gave four groups: S-LC, S-HC, C-LC and C-HC. All cows were inoculated with a live attenuated BHV-1 vaccine soon after parturition and the primary antibody response in whey monitored. The number of BHV-1 antibody positive cows was not significantly different between the four groups; but, the initial antibody response was lower in cows of high genetic merit which were given a low concentrate diet. Statistical analysis demonstrated that the contribution of diet to this effect was highly significant. One year later, again after parturition, the experiment was repeated, this time using serum as the test sample. The average antibody response of the BHV-1 antibody positive cows was not significantly different between the four groups but the number of antibody positive cows was group-dependent. In conclusion, diet type but not genetic merit for high fat plus protein yield made a highly significant contribution to the antibody response of dairy cows to BHV-1 vaccination, both initially and a year later.

Previous work (Metcalf et al 1996) has suggested that, even for cows when ME and MP supplies were balanced, the relationship between MP intake and net protein output at higher levels of feeding and production differs from that assumed in the MP system. This experiment was designed to test the concept that the efficiency of MP use for milk protein secretion is limited when metabolisable energy (ME) is limiting.

The objective of this study was to assess the growth and development of carcass composition of entire male and female lambs of three British hill breeds (Scottish Blackface, Welsh Mountain, and Shetland), from weaning to approaching maturity, when kept under conditions designed to be nutritionally non-limiting. Lambs were weaned at 8 weeks of age and given a high-quality pelleted diet ad libitum until slaughter at one offive different degrees of maturity. The Gompertz growth function was used to characterize, for each genotype, the growth curve and to provide estimates of mature weight. As expected, there were significant effects of breed and sex on both food intake and growth rate. Growth rate was depressed, relative to the Gompertz fit, during the months of October to January, and intake was similarly depressed. The estimates of mature weight for the females of each breed were: Scottish Blackface, 69; Welsh Mountain, 61; Shetland, 46 kg. The mature weights of the males were found to be not significantly different from 1-3 times the mature weight offemales. Relationships between carcass composition and live weight were derived by allometric regression. This study provides the first full description of the growth and meat production potential of the three breeds.

The accurate prediction of the food intake of cows is a necessary step in the formulation of dairy rations because the formulation to meet requirements will depend on the level of intake. Intake may change as lactation progresses. The way in which intake changes with stage of lactation on foods of different composition is therefore central to intake prediction systems. However, in the vast majority of existing experiments, the influence of stage of lactation on intake is confounded with changes in either the allocation of the ration or the composition of the diet. The results reported here are from the first part of an experiment which was carried out to provide, for the first time, intake data for dairy cows throughout lactation where diet composition remains constant.

Previous work at ADAS Bridgets aimed at evaluating the Metabolisable Protein (MP) system (AFRC 1992) has indicated that the efficiency of MP use for milk production may be too high, or that the amount of MP required for maintenance may be too low (Newbold et al 1994). This experiment was designed to indicate the true efficiency of MP use for milk protein production when metabolisable energy (ME) and MP supplies were balanced.

An experiment was designed to investigate whether the degree of synchrony between the rates of digestion of carbohydrates and N of foods offered as a choice would have an effect, through their consequences, on the short- and long-term diet selection of sheep. Four foods (RL, RH, SL and SH) with the same high metabolizable energy, and similar high metabolizable protein contents were made into pellets. Foods RL and RH were based on a rapidly fermentable carbohydrate source and foods SL and SH on a slowly fermentable carbohydrate source; within each source one food (RL or SL) had a low, and the other (RH or SH) a high, men-degradable protein (RDP) content. The foods within a carbohydrate source were offered either singly or as a choice (RI/RH or SI/SH) to eleven rumen-fistulated mature sheep. The design was two 3 x 3 Latin squares (replicated once) with 5- week periods; squares consisted of two single foods and their respective choice. Weeks 1, 3 and 5 were considered to be controls, and weeks 2 and 4 used for remen infusions of either urea or fructose infused over 4h (10·00-14·00 hours). Food intake (FI) and diet selections (DS) were recorded daily and every 2 h (08·00-16·00 hours) on days 2-5 of each week; m e n pH and NH3 concentrations were also measured during these time intervals of day 5. As expected, feeding treatment affected significantly the rumen measurements: m e n NH3 concentrations were higher on foods RH and SH, and men pH lowest on RL. Daily FI was lowest on treatments SL and choice SI/ The mean daily proportion of the low-RDP food in the selected diet was lower when the carbohydrate source was rapidly (choice RI/RH) rather than slowly fermentable (choice SI/SH); this was consistent with the experimental hypothesis. Short-term infusions affected further rumen variables (in the expected directions), irrespective of feeding treatment. However, DS over the 4 h infusion period were unaffected; these short-term DS were consistent with the ones selected over the longer term (daily). The results suggest that the long-term (daily) diet selection of sheep may be affected by the degree of synchrony of energy and protein to the men. The fact that diet selections were not altered further by short-term manipulations of these supplies might reflect inadequacies of the methodology (infusions) adopted here.

The present study tested the influence of protein undernutrition and re-alimentation on mammary gland size and secretory cell activity in lactating rats. During gestation, female Sprague-Dawley rats were offered a high-protein diet (215 g crude protein (N x 625; CP)/kg DM; H); litters were standardized to twelve pups at parturition. During lactation, two diets were offered ad libitum, diet H and a low- protein diet (90 g CP/kg DM; L). Lactational dietary treatments were the supply ad libitum of either diet H (HHH) or diet L (LLL) for the first 12 d of lactation, or diet L transferring to diet H on either day 6 (LHH) or 9 (LLH) of lactation. On days 1, 6, 9 and 12 of lactation, rats from each group (n > 6) were used to estimate mammary dry mass, fat, protein, DNA and RNA; the activities of lactose synthetase (EC 2.4.1.22) enzyme and Na+, K+-ATPase (EC 3.6.1.37) were also measured. Rats offered a diet considered protein sufficient (H) from day 1 of lactation showed a decrease in mammary dry mass and fat but an increase in DNA, RNA and protein on day 6, after which there was no further change, except for mammary protein which continued to increase. However, rats offered diet L showed a steady loss in mammary mass and fat throughout the 12 d lactation period and no change in mammary DNA, RNA or protein. Rats previously protein restricted for either the first 6 or 9 d of lactation had their mammary dry mass and mammary fat loss halted and showed a rapid increase in mammary DNA, RNA and protein on re-alimentation. Lactose production in group HHH, as measured by lactose synthetase activity, was similar on days 1 and 6 of lactation, after which a significant increase was seen. Protein- restricted rats showed no change in lactose synthetase activity during the 12 d experimental period. Changing from diet L to diet H led to a significant increase in lactose synthetase activity to levels comparable with those offered diet H from day 1. These results show that rats offered a protein-restricted diet during lactation suffer mammary underdevelopment, but this may be rapidly reversed by re-alimentation with a high-protein diet

There have been suggestions that positive feedback from the meal may stimulate the performance of undesirable behaviour, such as stereotypies, in the post-feeding period. The aim of this work was to measure the short-term effects of a meal on the post-feeding behaviour of the pig.

Pigs (70 kg live weight) were offered food ad libitum for 7 days and then given a restricted food allowance for 23 days (experiment 1) or 14 days (experiment 2). In experiment 1, the food allowance was given in one, two or three meals per day. In experiment 2, the food allowance was given in two meals per day and comprised ingredients which supplied glucose at different rates (starch, glucose/starch, starch/guar gum). The pigs' posture and behaviour were recorded in three 1-h periods during the day on 2 days consecutively during the ad libitum feeding period (time period 1) and on pairs of days on three (periods 2, 3 and 4: experiment 1) or two (periods 2 and 3: experiment 2) subsequent occasions during food restriction. The meal frequency or estimated rate of glucose supply had no significant effects on posture or behaviour. In both experiments activity increased with the duration of food restriction. In periods 1, 2, 3 and 4 of experiment 1 the proportions of observations spent were: standing 0·244, 0·260, 0·706 and 0·728 (s.e.d. 0·0346); nosing 0·073, 0·094, 0·229 and 0·253 (s.e.d. 0·0169); rooting 0·032, 0·037, 0·108 and 0·133 (s.e.d. 0·0133). In periods 1, 2 and 3 of experiment 2 the proportions were: standing 0·247, 0·302 and 0·446 (s.e.d. 0·0240); nosing 0·045, 0·075 and 0·138 (s.e.d. 0·0113); chewing 0·101, 0·126, 0·155 (s.e.d. 0·0121). In experiment 1 feeding rate increased with duration of restriction (P < 0·001), but was unaffected by treatment. It is concluded that post-feeding behaviour was influenced more by long-term changes in state (i.e. prolonged food restriction) than by short-term effects of the meal.