By tracing 14C after an injection of [U-14C] sodium acetate into the caecum of pigs, it was found that proportionately 0·93 of the acetate injected was absorbed. About 0·25 of the administered acetate was recovered in the body 96 h later. It is assumed that the remainder was oxidized during this period and exhaled as carbon dioxide.

The 14C initially predominated in plasma lipids, but it progressively shifted over the 96 h to plasma proteins. In the lipid fraction of blood plasma there was a continuous shift of 14C from triglycerides and free cholesterol to cholesterol esters over the 96-h period of measurement.

In the body most of the 14C was recovered in the fat, liver and intestinal wall. The highest concentration of 14C was in the bile, especially in glycine-conjugated bile acids.

It was shown that the absorbed acetate was a source of energy to the pigs and it was recycled and metabolized into more complex components in the body during 96 h.

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

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

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

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

A selection experiment with Scottish Blackface sheep was used to compare predicted and realized correlated responses to selection. Three lines were maintained between 1956 and 1974 in which selection was either at random or for high and low values of an index of cannon-bone length at 8 weeks of age adjusted for body weight at the same age.

There was no evidence of asymmetrical responses in any trait. Selection for increased cannon-bone length, adjusted for body weight, resulted in (i) increased body weights at all ages between birth and maturity, (ii) increased reproduction rate, principally from increased litter size but also from small responses in ewe fertility and lamb survival and (iii) decreased survival of adult ewes. The realized genetic correlations were relatively small (up to 0·3) but mostly significantly different from zero, whereas base population genetic correlation estimates were very imprecise. The realized responses in reproduction rate were probably a consequence of the genetic response in body weight.

The objective of this study was to examine the effect of dietary vitamin A (retinol) on leptin in cattle. The relationship between plasma leptin and insulin was also examined. The experiment studies 16 9-month-old steers over the following 20-month fattening period. Four treatment diets were given to four steers in each of four groups. Cattle in treatment A were given a diet high in vitamin A (9000 to 10500 µg/day) throughout the experiment. Cattle in treatment B were given a diet low in vitamin A (300 to 4500 µg/day) for 0 to 10 months, after that they were given the high vitamin A diet during the period 10 to 20 months. Cattle in treatment C were given the low vitamin A diet for 0 to 14 months, after that they were given the high vitamin A diet for the period 14 to 20 months. Cattle in treatment D were given the low vitamin A diet throughout the experiment. Plasma samples were collected at 2-month intervals during the experiment to determine the plasma leptin, insulin and vitamin A concentrations. Plasma leptin concentration significantly increased over the fattening period (P < 0·001) but did not differ between the treatments (P > 0·05). Plasma leptin concentration was positively correlated with insulin concentration (r = 0·44, P < 0·001), although it was not correlated with plasma vitamin A concentration (r = –0·01, P > 0·05). It was concluded that dietary vitamin A in cattle does not affect plasma leptin concentration.

The stomach and small intestine manifest a myoelectric activity pattern called the migrating myoelectric complex (MMC), which is controlled by both environmental and intrinsic factors. The daily MMC pattern has been little investigated, therefore the purpose of the present study was to study it, in weaned pigs given food twice a day. A wireless telemetric recording system was used for 24-h electromyography of the antrum and duodenum. The activity of the antrum showed little change if any, whereas the myoelectric activity of the duodenum significantly changed with respect to the time of day and feeding in conscious pigs. Namely, there were more frequent and regular MMC cycles occurring in the duodenum at night as compared with that during daytime. This change was due to the shortening of phase II of the MMC cycles that were registered at night. Phase I of the MMC showed transient variability in relation to feeding with no impact on the day/night differences. Phase III of the duodenal MMC cycle as well as the ‘feeding pattern’ did not change along with the time of day and feeding regime. In conclusion, daily variation in the duodenum may provide different conditions for digestive processes in the day and night.

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

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

Three groups, each of 12 West African Dwarf ewes weighing 17·5 kg at mating, had mean daily digestible organic matter intakes over the final 7 weeks of pregnancy of 249, 435 and 538 g/ewe (Treatments I, II and III respectively). Mean plasma concentrations in Treatments I, II and III were: glucose, 384, 527 and 538mg/l; non-esterified fatty acids (NEFA), 672, 441 and 427 μequiv/1; and ketones, 44·1, 30·5 and 27·3 mg/1. The differences in all metabolites between Treatment I and Treatments II and III were significant (i) <0·001). The mean birth weights of the single lambs from ewes in Treatments I to III were 1·1, 1·7 and 1·8 kg, those from ewes in Treatment I being significantly lighter than those from ewes in Treatments II and III. Lamb birth weights were significantly and positively related to energy intake and to plasma glucose concentrations, and significantly and negatively related to plasma NEFA and ketone concentrations.

The results indicate that the effect of undernourishment during late pregnancy in West African Dwarf sheep may be greater than in European breeds, and that the concentrations of blood metabolites may have a use in monitoring and regulating nutritional state in this genotype.

Re-esterified oils are new fat sources obtained from the chemical esterification of acid oils with glycerol (both economically interesting by-products from oil refining and biodiesel industries, respectively). The different fatty acid (FA) positional distribution and acylglycerol composition of re-esterified oils may enhance the apparent absorption of saturated fatty acids (SFA) and, therefore, their overall nutritive value, which might lead to an increased deposition of SFA. The aim of the present study was to investigate the potential use of re-esterified palm oils, in comparison with their corresponding acid and native oils in fattening pig diets, studying their effects on fatty acid apparent absorption, acylglycerol and free fatty acid (FFA) composition of feces, growth performance, carcass-fat depots and fatty acid composition of backfat. Seventy-two crossbred boars and gilts (average weight of 24.7±2.55 kg) were blocked by initial BW (nine blocks of BW for each gender), housed in adjacent individual boxes, and fed one of the four dietary treatments, which were the result of a basal diet supplemented with 4% (as-fed basis) of native palm oil (PN), acid palm oil (PA), re-esterified palm oil low in mono- and diacylglycerols (PEL), or re-esterified palm oil high in mono- and diacylglycerols (PEH). Regarding results from the digestibility balance, PA and PN showed similar apparent absorption coefficients (P>0.05), despite the high, FFA content of the former. However, re-esterified palm oils (both PEL and PEH) showed a higher apparent absorption of total FA than did their corresponding native and acid oils (P<0.001), mainly due to the increased apparent absorption of SFA (P<0.001). This resulted in a greater feed efficiency and an increased deposition of SFA in backfat of pigs fed PEH, when compared with those fed PA (P<0.05), although no differences were found for carcass-fat depots (P>0.05). We conclude that re-esterified oils are interesting fat sources to be considered in fattening pigs.

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

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

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

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

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

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

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

The effects of a moderate level of undernutrition on the release of luteinizing hormone (LH) at oestrus and after luteinizing hormone releasing hormone (LHRH) treatment was investigated. Plasma levels of glucose, non-esterified fatty acids (NEFA), cortisol and prolactin were also investigated.

During the early breeding season 10 mature ewes were placed on either a maintenance (M) or a restricted (R) diet. After 50 days of dietary treatment their oestrous cycles were synchronized and blood samples were taken over the oestrous period. Eight days later LHRH was administered and blood samples were taken for the following 6 h.

After 50 days of treatment mean body- weights were 66 (s.e. 4) and 53 (s.e. 3) kg, and mean body condition scores were 3·5 and 2·0 for the M and R groups respectively. The pre-ovulatory and LHRHinduced LH peaks were similar in both groups as were the prolactin profiles. However, plasma NEFA levels were elevated and glucose and cortisol levels were reduced in the restricted group.

It is concluded that the reduction in energy intake achieved in this experiment, although sufficient to cause significant metabolic changes had no effect on the release of LH either at oestrus or after LHRH treatment.

Remarkable increases in the production of dairy animals have negatively impacted their tolerance to heat stress (HS). The evaluation of the effect of HS on milk yield is based on the direct impact of HS on performance. However, in practical terms, HS also exerts its influence during gestation (indirect effect). The main purpose of this study was to identify and characterize the genotype by environment interaction (G × E) due to HS during the last 60 days of gestation (THI_g) and also the HS postpartum (THI_m) over first lactation milk production of Brazilian Holstein cattle. A total of 389 127 test day milk yield (TD) records from 1572 first lactation Holstein cows born in Brazil (daughters of 1248 dams and 70 sires) and the corresponding temperature–humidity index (THI) obtained between December 2007 and January 2013 were analyzed using different random regression models. Cows in the cold environment (THI_g = 64 to 73) during the last 60 days of gestation produced more milk than those cows in a hot environment (THI_g = 74 to 84), particularly during the first 150 days of lactation (DIM). The heritabilities (h2) of TD were similar throughout DIM for cows in THI_g hot (0.11 to 0.20) or (0.10 to 0.22), while the genetic correlations (rg) for TD between these two environments ranged from 0.11 to 0.52 along the first 250 DIM. The h2 estimates for TD across THI_m were similar for cows in THI_g hot (0.07 to 0.25) and THI_g cold (0.08 to 0.19). The rg estimates ranged from 0.17 to 0.42 along THI_m between TD of cows in cold and hot THI_g. The results were consistent in demonstrating the existence of an additional source of G × E for TD due to THI_g and THI_m. The present study is probably the first to provide evidence of this source of G × E; further research is needed because of its importance when the breeding objective is to select animals that are more tolerant to HS.

The responses in traits measured at the start of the mating period and at farrowing were examined after seven generations of divergent selection for daily food intake (DFI), lean food conversion (LFC), lean growth rate (LGA) on ad-\ibitum feeding and lean growth on scale feeding (LGS). Weight and backfat depth at mating were measured on 330 gilts and 74 boars, which were selected on the basis of performance test traits. Farrowing information was available on 259 gilts. At the start of the mating period, gilts selected for high DFI, LGA or LGS had similar live weights (135, 137 and 137 (s.e.d. 4·5) kg) but different backfat depths (20·3, 14·0 and 11·3 (s.e.d. 1·3) mm) while the corresponding low lines had different live weights (129, 117 and 124 kg), but similar backfat depths (17·5, 17·8 and 17·8 mm). Gilts selected for high LFC had lower mean live weight and backfat depth (114 kg and 10·7 mm) than gilts in the other selection lines. Conception rates of gilts selected for low DFI or high LGS were similar (0·62 and 0·64, s.e.d. 0·12) and lower than for the alternative selection strategies (0-78), but the low DFI gilts were significantly older at farrowing than gilts selected for high LGS (424 v. 408 (s.e.d. 5·5) days). Responses in live weight, backfat depth, age at mating and particular reproduction traits were selection strategy dependent, such that identification of relationships between growth and reproduction traits will require measurement of additional growth traits at an earlier age than in the current study

1. Homologous antibodies to Salmonella pullorum were produced by immunising pigs between 100 and 200 lb. live-weight.

2. Standardised doses of antibody, extracted from whole serum after these pigs were slaughtered, were administered to 245 piglets by stomach tube during the first 24 hr. after birth.

3. The marked variation in uptake of the marker antibody, determined by direct agglutination tests on the blood serum of the dosed pigs, was chiefly due to variation between litters. This variation was attributed to maternal effects, associated with agents secreted in varying quantities into colostrum. Concentration of antibody in the dose administered to piglets, time elapsing between birth and dosage and differences between sire families, were subsidiary causes of variation. Possible mechanisms influencing efficiency of antibody absorption were examined and discussed.

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

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

Many feedstuffs consist of a variety of proteins which, differing in size and structure, may undergo proteolysis in the rumen at different rates. The conventional use of single, constant coefficients to describe the proportion of protein degraded in the rumen (e.g. 0.65 for soyabean meal) may, therefore, be inappropriate. Soyabeans contain two major storage proteins, β-conglycinin and glycinin. Two experiments were conducted to assess differences in rate of proteolysis between α and β sub-units of β-conglycinin (molecular weight approximately 66kD and 56kD, respectively) and acidic and basic sub-units of glycinin (approximately 36kD and 23kD, respectively).

The growth of grass varies considerably from month to month. Where stock numbers are constant, as in a dairy herd, it is difficult to use grassland efficiently by grazing alone. But where grassland is used for meat production, livestock numbers may be subject to a considerable fluctuation, and with skilful adjustment of classes of stock this fluctuation can be made to approximate to the seasonal pattern of growth in the pasture.

The adjustment of stock numbers to the quantity of grass present is an art which is part of successful grazing management. Understocking will lead to an accumulation of pasture which will then have to be grazed at a more mature stage, while overstocking will result in a lower plane of nutrition for the animals. The efficiency of equating stocking intensity to the pasture available in a given period will be reflected in the progress of the individual animal (in terms of daily milk yield or live-weight gain) and in the output per acre of pasture.

Malic enzyme 1 plays a fundamental role in lipid metabolism because it yields a significant amount of the NADPH necessary for fatty acid biosynthesis. In ruminants, however, its contribution to this biochemical process seems to be less relevant than in other livestock species. In this study, we have partially sequenced the goat ME1 gene with the aim of identifying polymorphic sites. Structural analysis of the goat ME1 amino acid partial sequence evidenced the existence of two dinucleotide-binding motifs, located at positions 158 to 163 (GLGDLG) and 301 to 306 (GAGEAA), and three amino acid residues (E245, D246 and D269) involved in the binding of Mn2+ and strongly conserved among mammalian species. Moreover, multiple sequence alignment allowed us to identify four single nucleotide polymorphisms at exons 5 (c.483C > T), 6 (c.667G > A), 9 (c.927C > T) and 11 (c.1200G > A). The effects of ME1 genotype on milk production and composition traits were investigated in a Murciano–Granadina goat population. None of the associations found reached statistical significance after applying Benjamini–Hochberg correction. At most, associations with uncorrected P-values below 0.01 were observed for C16:0, C18:1n-9t and total conjugated linoleic acids. These negative results reinforce the notion that ME1 plays an ancillary role in ruminant lipogenesis.