Forty-eight Suffolk × Clun lambs were used in an experiment to investigate the effects of two times of removal from the dam and two feeding frequencies upon milk intake over the first 4 days on an artificial rearing system.

Lambs removed at birth consumed significantly more milk replacer at feeding periods up to 32 hr after removal than lambs removed at 24 hr after birth. Removal at birth also significantly increased voluntary milk intake between feeding periods for up to 32 hr and from 64 to 80 hr after removal.

Feeding the lambs during a 16-hr period in a 4, 4, 8 hr sequence instead of 8, 8 hr intervals significantly improved milk intake at feeding periods.

Changes in ultrasound measures of muscle area (UtM) during lactation in different breeds and parities and with different feeding levels were examined. Random regressions were fitted to repeated measures of UtM in order to study changes in variance components of UtM during lactation. Correlations between measures taken in different stages of lactation and in different parities were also calculated. The shape of UtM curves during lactation appeared to be fairly consistent for all breeds and parities. The lowest point of all curves coincided with the expected nadir of body reserves during lactation. With lower-than-normal feeding level, the drop of UtM after calving was deeper and the overall level was lower. A major proportion of the variance in UtM was found to be determined by additive genetic variation. In all three breeds studied, repeatability and heritability estimates were high and fairly consistent during lactation and between parities. The very high genetic correlations between measures taken in different periods of lactation suggested that muscle growth and recovery are controlled by the same gene complex throughout lactation.

Our results suggest that UtM, if used jointly with other body measures such as body condition score, could be a useful indicator of tissue mobilization and deposition in the lactating cow, especially during the early stage of lactation.

Concentrates-fed lamb meat is often associated with an unfavourable lipid profile (high levels of saturated and/or n-6 polyunsaturated fatty acids; SFA and PUFA). For this reason, Spanish sheep producers from Mediterranean areas are turning to traditional grazing by ewes to obtain healthier lamb meat. The objective of this research was to determine the effects of maternal grazing on the fatty acid (FA) composition of weaned lamb meat. The ewes (Segureña breed) were allocated to two different rearing systems during pregnancy (5 months) and lactation (45 days): (i) feeding indoors on barley grain and lucerne pellets; (ii) grazing on cereal stubble, fallow land and seasonal pastures consisting of Mediterranean shrubs, herbs and trees. Two groups of 20 autumn and spring lambs were sampled. The lambs were weaned at 13.1±0.9 kg and 45.0±4.1 days age and fed on grain-based concentrates until they reached 24.8±2.1 kg live weight (light lambs slaughtered at 98.3±3.6 days of age). The FA content was determined in the intramuscular loin fat by gas chromatography using a flame ionization detector. The ewe diet did not affect the levels of the main lamb FAs (C18:1c+t, C16:0 and C18:2c), and so did not provide any additional reduction in fat saturation. Saturated fatty acids represented around 40% of total FAs determined in the meat. Ewe grazing acted as an n-3 PUFA-promoting diet, providing a lamb meat with a lower n-6/n-3 ratio. Spring lamb meat had higher proportions of n-3 PUFA (C18:3n-3, C20:5, C22:5 and C22:6) and conjugated linoleic acid (C18:2c9t11+c11t9) to the detriment of the n-6 PUFAs (C20:4, C20:2 and C22:4), while autumn lamb meat also had higher levels of C18:3n-3 and C18:3n-6, and lower level of C20:4, which points to little seasonal differences. The n-6/n-3 ratio achieved by ewe grazing fell from 8.2 to 4.1 (Spring) and from 7.6 to 5.5 (Autumn), values which are close to those recommended in human diet for good cardiovascular health. These n-6/n-3 reductions were associated with lower levels of total PUFA and C20:4n-6. Our research concluded that grazing on stubble and Mediterranean shrubland by ewes, a sustainable rearing practice involving local agro resources, contributed to obtaining weaned lamb meat with a more favourable lipid profile and so can be recommended to sheep farmers.

The aim of this study was to investigate the effect of including milk yield data in the international genetic evaluation of female fertility traits to reduce or eliminate a possible bias because of across-country selection for milk yield. Data included two female fertility traits from Great Britain, Italy and the Netherlands, together with milk yield data from the same countries and from the United States, because the genetic trends in other countries may be influenced by selection decisions on bulls in the United States. Potentially, female fertility data had been corrected nationally for within-country selection and management biases for milk yield. Using a multiple-trait multiple across-country evaluation (MT-MACE) for the analysis of female fertility traits with milk yield, across-country selection patterns both for female fertility and milk yield can be considered simultaneously. Four analyses were performed; one single-trait multiple across-country evaluation analysis including only milk yield data, one MT-MACE analysis including only female fertility traits, and one MT-MACE analysis including both female fertility and milk yield traits. An additional MT-MACE analysis was performed including both female fertility and milk yield traits, but excluding the United States. By including milk yield traits to the analysis, female fertility reliabilities increased, but not for all bulls in all the countries by trait combinations. The presence of milk yield traits in the analysis did not considerably change the genetic correlations, genetic trends or bull rankings of female fertility traits. Even though the predicted genetic merits of female fertility traits hardly changed by including milk yield traits to the analysis, the change was not equally distributed to the whole data. The number of bulls in common between the two sets of Top 100 bulls for each trait in the two analyses of female fertility traits, with and without the four milk yield traits and their rank correlations were low, not necessarily because of the absence of the US milk yield data. The joint international genetic evaluation of female fertility traits with milk yield is recommended to make use of information on several female fertility traits from different countries simultaneously, to consider selection decisions for milk yield in the genetic evaluation of female fertility traits for obtaining more accurate estimating breeding values (EBV) and to acquire female fertility EBV for bulls evaluated for milk yield, but not for female fertility.

Antibiotics have been widely used in piglet diets to promote growth performance and reduce diarrhea incidence. However, the resistance of pathogens to antibiotics and the risk of residues of antibiotics in animal products induced a growing interest in the use of alternatives to in-feed antibiotics. Chito-oligosaccharide (COS), a natural alkaline polymer of glucosamine is currently being tested as a substitute for in-feed antibiotics. In weaned piglets, COS has positive effects on promoting growth, which may be related to its action on intestinal morphology, immune ability and beneficial microbiota. However, previous studies shown variable results with effective doses ranging from 30 mg/kg to 5 g/kg. Therefore, the goal of this study was to test the hypothesis that the use of COS can be an alternative to in-feed antibiotics by improve the intestinal morphology of piglets, using the jejunal explant model. The intestinal explants were exposed for 4 h to following treatments: control – only culture media and culture media with COS in doses of 0.025 mg/ml, 0.05 mg/ml, 0.1 mg/ml and 0.15 mg/ml. After the incubation period the explants were processed for histological and morphometrical analysis. The histological changes were evaluated using an adapted histological score based on the intensity and severity of lesions. Mild histological changes were observed in jejunal explants exposed to different treatments; however, no significant difference in the histological score, villi height, crypt depth or villus : crypt ratio were observed between the COS-groups and the control. In addition, goblet cells density in intestinal explants exposed to COS remained statistically similar to control group. Our results indicate that COS exposure in levels ranging from 0.025 to 0.15 mg/ml induced no effect on intestinal morphology of pig’s explants. The research will provide guidance on the low dosage of COS supplementation on weaning pigs.

N-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) are subject of growing interest as they are of particular relevance for meat quality and human health. However, their content in the muscles of cattle is generally low probably as the complex result of their biosynthesis from dietary n-3 PUFA in the muscle and/or in other tissues/organs and of their subsequent uptake by the muscle. In view of this, this study aimed at understanding whether the changes in the muscle n-3 LCPUFA content, depending on the diet (maize silage v. grass) or the muscle type (Rectus abdominis, RA v.Semitendinosus, ST) in 12 Charolais steers, were related to variations in the gene expression of proteins involved in n-3 LCPUFA biosynthesis or cellular uptake. Tissue fatty acid composition was analysed by gas-liquid chromatography and mRNA abundance of proteins by quantitative real-time PCR. The grass-based diet resulted in a 2.3-fold (P < 0.0002) increase in both RA and ST n-3 LCPUFA content compared with the maize silage-based diet, whereas no difference in the expression of genes involved in n-3 LCPUFA biosynthesis and uptake was observed between diets. ST exhibited a 1.5-fold higher n-3 LCPUFA content than RA (P < 0.003), whereas the gene expression of proteins involved in n-3 LCPUFA biosynthesis and uptake was 1.3- to 18-fold higher in RA than in ST (P < 0.05). In conclusion, diet- or muscle type-dependent changes in the muscle n-3 LCPUFA content of Charolais steers did not seem to be mediated by the gene expression regulation of proteins involved in the biosynthesis or uptake of these fatty acids.

One of Bertrand Russell's contributions to philosophy was to show that there are certain questions, quite simple to state, to which no sensible answer can be given. While writing this paper I began to feel that the question ‘what is the optimum size of the dairy cow ?’ is perhaps among these. Let me first ask what we mean by the question, what assumptions we have to make to answer it, and finally what use is the answer.

Current techniques for in vitro digestion of forages depend on the use of rumen fistulated animals to supply microbial suspensions in rumen liquor. The objective of the present study is to develop a noninvasive alternative to rumen liquor as a source of micro-organisms in the two-stage, in vitro digestion technique of Tilley and Terry (1963).

EL Shaer, Omed, Chamberlain and Axford (1987) showed a high correlation between digestibility in vitro determined using micro-organisms from rumen liquor and from freshly-voided sheep faeces. The disadvantages of using sheep faeces are (a) the need for fresh faeces, (b) the small quantities voided at any given time and (c) the difficulty of enticing sheep to defaecate at a specific time.

Cow faeces as a source of micro-organisms was investigated in the present study because of the ease of collecting a large quantity of freshly-voided faeces at a given time. Another objective of the present study was to investigate whether faeces could be frozen and stored for future use as a source of micro-organisms for the in vitro digestibility assay. A further objective was to investigate whether rumen liquor could be frozen and stored for future use.

Recent legislation prohibiting the use of individual confinement systems for dry sows has led to the adoption of group housed systems which have perceived welfare advantages. The feeding system for dry sows and gilts is fundamental to welfare and production; problems such as abnormal behaviours, aggression and psychological stress, caused by poor nutrient distribution in group systems, must be addressed.

In this study the relative merits of three feeding systems for group housed gilts were investigated in relation to welfare and production.

Enzymic hydrolysis of phytates has been shown to improve the apparent digestibility of phosphorus. Other nutrients bound to phytates may be released during phytate degradation by phytases. Dietary yeast may also improve the availability of phosphorus to pigs by altering gut fermentation patterns.

The objectives of this experiment were (1) to study the effects of phytase on the apparent digestibility of phosphorus and other nutrients associated with phytates, and (2) to determine whether an alteration in fermentation induced by dietary yeast inclusion influenced availability of phosphorus.

Live-weight growth was studied for 64 female, 64 castrated male and 64 intact male indigenous Nigerian pigs at 16 ages from birth to 672 days. The weights obtained were fitted into four different growth functions to derive prediction equations for the models used. The quadratic (W = a + bt + ct2) and the Schmalhausen functions (W = at) described live-weight growth better than the simple linear function fW = a + bt). Estimating live-weight growth using Brody's function (Y = aebt) gave the least exact predictive ability. Linear growth in indigenous Nigerian pigs occurred between 112 and 336 days. Castrated male pigs exhibited higher live-weight growth rates than either the female or intact male pigs. Differences in the prediction of live weights using the four growth functions and the actual live weights are presented and discussed.

1. Performance tests were made on 221 bulls of eight breeds or crosses from 90 days of age (weaning) up to 400 kg live weight. Feeding was in individual pens on a high-energy complete diet.

2. Pre-weaning gain was not significantly related to gain on test (r = 0·11) nor was 90-day weight to gain on test (r = 0·26) or feed conversion (r = −0·15). Weight for age at 200 and 300 kg was highly correlated with final weight for age (r = 0·72 and 0·89 respectively) while gain on test and final weight for age had a pooled correlation (across breeds) of r = 0·95. The correlation of feed conversion with gain on test was highly significant in all breeds. The range of values (−0·72 to −0·86) is higher than any previously reported estimates possibly due to an absence of initial weight effects, a reduction in the proportion of feed used for maintainenance and the use of complete diets.

3. It is suggested that with this testing system at least 50% of bulls could be culled at 300 kg without affecting selection of the best 20% of all bulls starting the test.

Two experiments were performed to examine the effects of immunoneutralizing PMSG at the onset of oestrus on the reproductive performance of sows. In experiment 1, 12 multiparous sows received 750 i.u. PMSG at weaning and six sozus acted as controls and were injected with saline. At 84 h after PMSG injection, all sows received an injection of 500 i.u. human chorionic gonadotropin (hCG) and six of the PMSG-treated sows also received an injection of 750 i.u. of a monoclonal anti-PMSG serum. The ovaries of all sows were examined by real time ultrasonography at 60-min intervals from 36 to 48 h after hCG injection for evidence of ovulation. In sows observed to ovulate, there was no significant effect of treatment on the interval from hCG injection to the start of ovulation, the duration of ovulation or subsequent litter size. In experiment 2, 253 primiparous sows received injections at weaning of 750 i.u. PMSG (no. = 134), 400 i.u. PMSG plus 200 i.u. hCG (no. = 69) or served as controls (no. = 50). At breeding, 67 of the PMSG-treated sows received an injection of 750 i.u. of monoclonal anti-PMSG serum.

More gonadotropin-treated than control sows were bred by 7 days after weaning (P < 0·05). Farrowing rates were higher in sows receiving the PMSG followed by anti-PMSG and PMSG plus hCG than in controls (P < 0·05), with those receiving PMSG alone being intermediate. There was no effect of treatment on subsequent litter sizes. These data indicate that the reproductive performance of primiparous sows may be improved by gonadotropin administration at the time of weaning. However, there was no advantage to using any particular hormone combination or anti-PMSG.

Thirty-two British Friesian calves were individually offered milk substitutes ad libitum twice daily for 12 weeks. The milks were reconstituted to contain 170, 200, 230 or 260 g dry matter (DM) per kg, using spray-dried skim milk powder and homogenized fat-filled powder containing 500 g fat per kg. Drinking water was available ad libitum at all times. The last two blocks of four calves were used to measure the digestibility, absorption and retention of the constituents of the diets at 2, 6 and 11 weeks of age.

The DM intakes of the calves given the four diets were variable but generally increased with increasing DM concentration, mean values being 61·5, 59·5, 66·0 and 73·3 g DM per kg M0.75. As the calves increased in age, their intakes decreased from 67·3 g DM per kg M0.75 at 2 weeks of age to 61·1 g DM per kg M0.75 at 8 weeks of age.

The higher DM concentrations and intakes were associated with the higher rates of weight gain; the mean live weights at 12 weeks of age being 121·8, 123·9, 135·3 and 141·6 kg for the calves offered milks reconstituted at 170, 200, 230 and 260 g DM per kg respectively.

The concentration of the DM had no effect upon the coefficients of digestion or absorption nor on the retention of energy, protein, calcium or phosphorus. The digestibility of protein increased, whilst the absorption and retention of Ca and P declined with age.

Intake of drinking water did not change with age, but was higher for calves given the milk containing 260 g DM per kg than for those given the other three concentrations. The total water intakes were similar for the calves given milks containing 200, 230 and 260 g DM per kg.

The linear relationship of DM intake to DM concentration of the milk substitute suggested a lower level of intake in the present experiment, than was observed in a previous experiment (Ternouth, Stobo, Roy and Beattie, 1985b) when the milk concentrations were lower and drinking water was not available. When the concentrations of the DM were re-calculated to take into account the quantity of drinking water consumed, the relationships between DM intake and adjusted DM concentration for the two experiments were similar.

Eight trials involving 522 fattening lambs were conducted to compare rations of shelled corn and either long or chopped alfalfa hay with complete pelleted rations containing various proportions of concentrate.

Feeding lambs on complete pelleted rations that contained 50–100% roughage resulted in increased feed consumption and significantly greater gains. However, efficiency of feed conversion was improved by pelleting in only one trial.

Feed consumption and rate of gain were not improved by pelleting ground ear corn. Conversely, lambs fed only pelleted alfalfa hay gained significantly faster than lambs fed only chopped hay.

Sixteen Hereford-cross cattle (mean live weight 263 kg) in groups of four were individually given 1·5 kg cubed barley per day with ad libitum access to oat straw. In a 4 × 4 Latin square design (21-day feeding periods) they were additionally given either no supplement (diet A) or 100g/day of a fully soluble liquid supplement containing urea (equivalent to 1090 g crude protein per kg), calcium, phosphorus, sodium, trace elements and vitamins, presented either in the cubed barley (diet B), in the drinking water (diet C) or in a molasses lick (3 parts molasses:2 parts liquid supplement:1 part water) (diet D). Each method of supplementation significantly increased the mean voluntary straw dry-matter intake from approximately 2·9 to approximately 3·25 kg. Mean blood urea concentrations were significantly increased from approximately 1·0 to approximately 1·9 mmol/1 by all three treatments. The coefficients of variation for the individual blood-urea values of the cattle when given each of the three treatments were very comparable, indicating that there was a reasonable individual uniformity of intake of liquid supplement irrespective of method of presentation.

Wild yak males were crossed with domesticated female yaks to produce a breeding herd of crossbred animals. The milk production of the progeny of this herd was measured in the present study. Yaks were milked once daily after prior suckling of the calf. Yaks were allowed to graze for 15 hiday on high-altitude (3200 to 3500 m) pastures. No supplementary food was given. Average daily milk yield of 1·77 (s.e. 0·16) kg and milk yield over 120 days, 212·2 (s.e. 20·2) kg were significantly higher (P < 0·01) than the corresponding figures for unimproved domestic yaks (1·53 (s.e. 0·10) kg and 184·6 (s.e. 10·5) kg respectively). The fat content of milk from crossbred yaks, 52 (s.e. 2·9) glkg, was not significantly different from that of unimproved animals, 53·5 (s.e. 4·1) g/kg.

The feeding value of three forms of acid-treated moist barley, viz. 26 % moisture and either rolled or plate-milled, and 29 % moisture plate-milled, was compared with that of dried hammer-milled barley for growing pigs from 23 to 87 kg live weight. Two feeding experiments were undertaken, one in which individual pigs were given the same amount of dry matter from all the diets, while in the other, groups of pigs were fed ad libitum. Digestibility of the diet was determined in a third experiment.

In both feeding experiments differences between treatments in efficiency of utilization of dry matter in the feed were significant (P<0·05), that for the diet containing dried barley being approximately 5% better than the other three. There were no significant differences between treatments in intake of dry matter, rate of growth and carcass quality of the pigs. However, pigs fed on dried barley apparently grew more rapidly than those given any of the acid-treated moist barleys. Differences in digestibility of the diets were very small and not significant except for crude protein. Differences in digestibility of protein (P<0·05), however, were not consistent with differences in efficiency of conversion of dry matter in the feed.

The effects of a dietary supplement with calcium salts of fatty acids and methionine hydroxy analogue on reproductive performance, blood metabolites, milk production, milk composition, body weight and body condition score was studied in lactating dairy cows. Autumn-calving, Holstein-Friesian cows (no. = 162) were assigned 1 week post calving to one of two diets: (1) unsupplemented maize-silage-based complete diet while housed before turn-out to perennial ryegrass pasture and (2) the same diet with 400 g per cow per day of a supplement with calcium salts of long-chain fatty acids and methionine hydroxy analogue (Megalac Plus, Volac Ltd). Eleven cows were removed from the study following randomization for reasons not related to the experiment leaving 151 cows on dietary treatments. The diets were offered until the end of the 18-week breeding period. Cows receiving supplement had higher milk yield and milk lactose production and lower milk protein and milk fat proportion (P < 0·05). Body weight and body condition scores were not different between treatments in the first 20 weeks of lactation (P > 0·05). Overall reproductive performance was not different between dietary treatments (P > 0·05). However, first lactation animals (no. = 33) receiving the dietary lipid and methionine supplement tended to have increased conception rates to first and second service (P < 0·09) which resulted in a shorter calving-to-conception interval in those animals (P < 0·06). Services per conception (P < 0·08), services per cow served (P < 0·05) and services per conception for pregnant cows (P < 0·05) in first lactation animals was reduced in the supplemented group. Although plasma cholesterol concentrations were increased following lipid and methionine supplementation (P < 0·01), plasma progesterone concentrations on day 5 and day 8 after artificial insemination were not different between dietary treatments (P > 0·05). In conclusion, a dietary supplement of calcium salts of fatty acids and methionine hydroxy analogue increased milk yield, milk lactose production and blood cholesterol concentration but did not improve reproductive performance, except in first lactation cows.

The objective of this work was to determine the apparent bioavailability of magnesium from four different types of calcined magnesites of Greek origin. These four types (A, B, C, D) were different in particle size fractions and production process. The solubility of the above four magnesium samples and their fractions were determined: (a) in the laboratory using ammonium nitrate solution after 24-h shaking and (b) in vivo using a nylon bag technique after 24-h incubation.

Solubility was correlated with apparent bioavailability as determined in a balance experiment with five wether sheep in a 5×5 Latin-square design.

Sheep were kept in metabolism cages and were given daily a basal diet (500 g hay + 700 g concentrate) plus 2 g magnesium supplements from types A to D. The magnesium bioavailability of the basal diet was used as a base for the determination of the bioavailability of magnesium in A, B, C and D supplements.

Magnesium apparent bioavailability of the basal diet was found to be 0·203 and, for the supplements A, B, C and D, 0·381, 0·339, 0·315 and 0·292 respectively. The solubility of supplements A, B, C and D in ammonium nitrate solution and in vivo (using the nylon-bag technique) was found to be 0·812, 0·805, 0·784 and 0·773 or 0·294, 0·152, 0·102 and 0·200 respectively.

The solubilities of the magnesium supplements in ammonium nitrate solution and in vivo both reflected dietary bioavailability differences up to a point, but neither was well enough correlated with the apparent bioavailability as determined by the balance experiment, this being judged to be the most precise method for bioavailability determination.