Successful and timely rebreeding is of major importance to the economics of suckler cow enterprises. Research into the causes of reprodutive failure and extended calving intervals can be difficult, not least because of the need for experiments involving large numbers of animals if statistically significant treatment effects are to be demonstrated. Useful information however, can be obtained from the analysis of data derived from a number of relatively small-scale experiments, not necessarily on reproduction per se, but in which records of reproductive performance are available.

This paper deals with the analysis of data on the reproductive performance of beef cows used in a number of experiments on the effects of nutrition during pregnancy and lactation on components of production such as milk yield and composition, calf birth weight and early calf growth rate. The objective of the analysis was to identify the major factors affecting calving interval and to quantify the magnitude of the effects of these factors.

In order to evaluate the genotype of the calpastatin (CAST) gene and its relationship to muscle histology and other post mortem traits in the Jinhua × Piétrain F2 pig family, 158 barrows and gilts were electrically stunned and exsanguinated. Both blood and muscle samples were collected, and both post mortem traits and meat qualities were recorded. Restriction fragment length polymorphism (RFLP) analysis, the periodic acid Schiff reaction (PAS) and myosin heavy-chain immunohistochemistry were employed to explore the relationship between genotype and muscle histology. Based on PAS reactivity, muscle fibres can be classified into three types: PAS (−), PAS (+) and PAS (++). Myosin heavy-chain immunohistochemistry can differentiate muscle fibres into either slow or fast fibres; the proportion of slow and fast fibres were 6% and 94%, respectively. When the amplification products of the CAST gene were digested with MspI, HinfI and RsaI, two different cleavage patterns could be discriminated from the endonuclease map detected using each enzyme. The results showed that the polymorphisms detected using these three endonucleases are identical. Only three genotypes (AA/CC/EE, AB/CD/EF and BB/DD/FF) were distinguished. Their frequencies were 0.1835, 0.5823 and 0.2342, respectively. Different genotypes had significant association with area and pH45m value of loin muscle, while showing no significant association with the water-holding capacity and conductivity of loin muscle. The results also revealed that the genotypes had a significant correlation with diameter, area, circularity and the aspect ratio of muscle fibres. It was also presented that the genotypes significantly correlated with the percentage of intramuscular connective tissue.

The effect of recombinantly derived bovine somatotropin (bST) administration on wool follicle populations, wool growth and body growth was examined in young lambs. Romney × (Border Leicester × Romney) lambs were treated with bST at doses of 0·1 or 0·3 mg/kg live weight per day, or with excipient, commencing on the day of birth and continuing at weekly intervals until the last injection was given at 11 weeks of age. Concentrations of immunoreactive somatotropin in plasma were 19·2 (s.e. 2·1), 65·2 (s.e. 2·8) and 74·7 (s.e. 4·8) μgll in the control, low dose bST and high dose bST groups, respectively. Somatotropin treatment did not alter the density of primary (P) or secondary (S) follicles in the skin, or the S/P ratio, as measured by histological examination of mid-side skin biopsy samples at 14 weeks of age. Mid-side greasy and clean wool growth during weeks 2 to 14 of the study were increased (P < 0·05) in bST-treated lambs but treatment had no effect on wool growth during the immediate post-treatment period (weeks 14 to 22), or on yearling fleece weight or wool quality characteristics. Body growth was not altered by bST administration. It is concluded that bST treatment stimulates wool growth even in very young lambs but, contrary to the results of a previous study, does not alter the development of wool follicle populations.

Forage crops of the genus Brassica are known to contain goitrogens which under certain conditions can cause severe incidences of neonatal mortality in lambs and goitre in older sheep (Shand, 1952; Sinclair and Andrews, 1958, 1959, 1961; Andrews and Sinclair, 1962).

In the course of studies of certain aspects of lamb growth it was noted that lambs grazing rape (Brassica napus) had heavier thyroid glands than comparable lambs grazing grass. Pipes, Premachandra and Turner (1958) found that a degree of hypothyroidism increased the rate of fattening and influenced the carcass quality of cattle, and in view of this and other evidence it was decided to test the hypothesis that changes in the weight of the thyroid glands of lambs grazing rape were associated with changes in the rate of live-weight gain.

Electrophoretic variants of certain red cell esterases of rabbits (Oryctolagus cuniculus) have been shown to be under the control of two co-dominant autosomal alleles (Grunder, Sartore and Stormont, 1965). Each allele controls two zones of esterase; those controlled by EsA migrated ahead of those controlled by EsB. The heterozygote manifests not only the zones of both homozygotes but also a ‘hybrid’ zone which appears between the A and B zones.

Hyaluronic acid (HA) is a polysaccharide preferably extracted from cockerel combs and used for medical purposes, mainly eye surgery. One way of increasing the production of HA from cockerels is to increase the size of the combs. The aim of this work was to study comb development and quantify direct and correlated responses for comb size at different ages and comb weight in two lines of White Leghorn selected for comb size at two different ages. Two lines were created, one selected for comb size at 16 weeks of age (CS16) (line E = early comb development) and the other for comb size at 29 weeks of age (CS29) (line A = adult comb size). There were between 500 and 800 birds of each line and generation and the lines had been selected for five generations. Cockerels in line E developed the combs at an earlier age and had smaller 29-week combs compared with the cockerels in line A. Genetic gain for the selection trait in generation five, measured in relation to line means in generation 1, was 58% in line E and 36% in line A. The corresponding correlated response for CS29 and comb weight (CW) in line E was 28% and 25% respectively, while for CS16 and CW in line A it was 46% and 35%. The results indicated that it is possible to increase cockerel comb size at both 16 and 29 weeks of age through selection.

There is a general need for higher objectivity and accuracy in describing the physiological fertility performance of dairy cows. To develop the alternative meaningful starting points for the selection of genetically superior dairy cows, this study focused on the detection of low progesterone concentrations, which are indicative of estrus events. Three mathematical approaches were used: one based on the exponentially weighted moving average control chart, and two threshold methods, which were developed in-house. Data were collected from one data set that included 97 insemination data of first-lactating Holstein dairy cows, and a second set that included 160 inseminations of primiparous and multiparous Holstein dairy cows. On the basis of these 2 data sets, and using a threshold of 1.2 ng progesterone/ml skimmed milk, the sensitivity of the 3 models was high and ranged between 100% and 93.13%, with an error rate between 4% and 22.17%. The specificity varied between 97.92% and 99.93%. The average concentration levels of true-positive–detected progesterone measures were low and ranged between 0.18 and 0.28 ng progesterone/ml skimmed milk (first data set) and 0.21 to 0.26 ng progesterone/ml skimmed milk (second data set). False-positive–detected low progesterone concentrations during estrus events were closely related to progesterone values around the 1.2 ng progesterone/ml skimmed milk threshold and the detecting rules of the control chart. Thus, we suggest that a threshold of 0.8 ng progesterone/ml skimmed milk is indicative for luteal activity in defatted foremilk. By means of the three methods used, the detection of low progesterone concentrations was possible and it can be assumed that this is a good starting point for further studies (such as interval calculation) in this area.

Experiments in Denmark and America and studies in this country have shown that the law of diminishing returns applies to the complex relationship between the food intake of the cow and her milk yield, that is, as the food intake of the cow increases, milk yield increases but at a constantly declining rate, so that a higher level of feeding produces a greater additional quantity of milk when the plane of nutrition of the cow is already low. The optimal level of feeding dairy cows for profit cannot therefore be fixed for it must vary with both the cost of the cow’s food and the selling price of milk.

Increased plasma α-1 acid glycoprotein (AGP) is correlated with reduced growth rates in neonatal swine. The specific physiological mechanisms contributing to this relationship are unknown. This study was performed to determine if AGP can modify muscle metabolism by examining glucose oxidation and protein synthesis in the C2C12 muscle cell line. Cells were used for experiments 4 days post-fusion as myotubes. Myotubes were exposed to AGP for 24 h, with the last 4 h used to monitor 14C-glucose oxidation or to measure protein synthesis by incorporation of 3H-tyrosine. Treatment of C2C12 myotubes with mouse AGP (100 µg/ml) reduced glucose oxidation (P<0.01, n=3 trials), whereas bovine insulin (1 µM) stimulated glucose oxidation (P<0.05, n=3 trials). Treatment with AGP in combination with insulin reduced 14C-glucose oxidation (P<0.05, n=3 trials), similar to the effect of AGP alone. Glucose transport, as measured by 3H-deoxyglucose uptake, was increased by 38% with 1 µM insulin (P<0.05, n=3 trials), whereas AGP alone increased glucose uptake by 36% (P<0.05, n=3 trials). The combination of insulin and AGP in the medium resulted in an 88% increase in glucose uptake (P<0.01, n=3 trials). Protein synthesis was measured by 3H-tyrosine incorporation into C2C12 myotubes. Insulin stimulated a 18% increase in 3H-tyrosine incorporation (P<0.05, n=6 trials). The incorporation of 3H-tyrosine into myotubes was reduced by 20% with AGP incubation (P<0.01, n=6 trials), like the 20% decrease in 3H-tyrosine incorporation in response to the combination of AGP and insulin (P<0.01, n=6 trials). Protein breakdown, as measured by the release of 3H-tyrosine from C2C12 myotubes, was reduced 27% by insulin (P<0.01, n=6 trials). Treatment with AGP had no effect on protein breakdown (P>0.05, n=6 trials), whereas incubation with both AGP and insulin reduced 3H-tyrosine release by 15% (P<0.01, n=6 trials). First, these data indicate that the acute phase protein AGP can interact with the skeletal muscle to reduce glucose oxidation, but this is not the result of an effect on glucose transport. Second, AGP can specifically reduce protein synthesis. Lastly, AGP can inhibit insulin-stimulated glucose oxidation, protein synthesis and breakdown.

Determining energy utilization in growing animals enables to adjust the nutritional constraints to nutrient requirements while maximizing the ratio between lean retention and fat retention to improve feed efficiency. In turkey production, the important sexual dimorphism and differences between strains may contribute to differences in basal energy metabolism and the partitioning of energy retention between protein and lipid. The objective of this study was to determine the dynamics of energy utilization in males and females of a heavy strain of turkeys fed ad libitum from 1 to 23 weeks of age. Heat production (HP) was determined by indirect calorimetry and retained energy (RE) was calculated as the difference between metabolizable energy (ME) intake and HP. The RE as protein was determined by a nitrogen balance, while the remaining RE was assumed to be lipid. A modeling procedure allowed partitioning HP between fasting HP (FHP), activity-related HP and thermic effect of feeding. A multiple regression analysis was used to estimate the maintenance energy expenditure (MEm) and the energy efficiencies of protein and lipid retention (kp and kf, respectively). Results were expressed either per day or per kg BW0.75 per day. In comparison with females, males consumed more feed (440 v. 368 g/day), grew faster (163 v. 147 g/day) and retained more protein (38 v. 28 g/day) during the experimental period. Expressed per kg BW0.75 per day, ME intake decreased linearly with increasing age and was not affected by gender. Similarly, RE as protein decreased with increasing age and tended to be greater in males than in females, whereas RE as lipid increased with increasing age and was lower in males than in females. In addition, HP decreased with increasing age and was greater in males than in females, because of greater activity-related HP and FHP (47% and 9% greater in males compared with females). The FHP averaged 417 kJ/(kg BW)0.75 per day during the first 3 weeks of age and decreased to 317 and 277 kJ/(kg BW)0.75 per day in males and females, respectively, from 20 weeks of age onwards. Similar to FHP, MEm was lower in females than in males ((586 to 12 × BW) and (586 to 5 × BW) kJ/(kg BW)0.75 per day, respectively) and the kp and kf were estimated at 0.63 and 0.87, respectively. This study shows that the partitioning of RE and HP differs between genders in growing turkeys, which likely results in differences in nutrient requirements.

Teat diameters of 144 British Friesian cows were measured (1) at the proximal end of the teat and (2) 20 mm above the distal end before and after milking. Proximal minus distal diameter—‘teat diameter gradient’is used to describe shapes varying from cylindrical to funnel-shaped. Proximal and distal teat diameters and teat diameter gradient had higher values before milking than after milking. Teat diameter, teat diameter gradient and difference in gradient before and after milking, were positively correlated with milk yield and negatively correlated with somatic cell count.

The voluntary intake and apparent digestibility of kleingrass (Panicum coloratum cv. Verde) were measured in seven periods, comprising one full year. The forage was offered twice a day ad libitum to seven rams, fitted with faeces collection bags; each experimental period was composed of 8 days for adaptation and 8 days for collection of data. The dry-matter (DM) intake (DMI) varied from 36·1 to 64·9 glkg M075, the digestible dry-matter intake (DDMI), from 17·4 to 41·9 glkg M0·75 and the in vivo dry matter apparent digestibility (DMD), from 0·471 to 0·667.

Daily samples of offered forage were taken and pooled subsamples from each of the seven periods were incubated in nylon bags in the rumen of three Hereford steers. The data were fitted to the exponential equation: p = a + b (1-e-ct) to estimate p (the proportionate loss of DM at time t of incubation); effective degradability (ED) and lag time (L) were also estimated.

The parameters obtained in situ were related to the in vivo results by simple and multiple regression. The correlation coefficients of the rate of degradation (c) and ED with DMI, DDMI and DMD were, respectively, 096 and 0·97; 0·97 and 0·96; 0·86 and 0·88. By including a, b, c and L into a multiple regression analysis, the coefficients of determination (R2) were: DMI: 0·99; DDMI: 0·99 and DMD: 0·91. Within the conditions of this study, the parameters obtained in situ were reasonable estimators of voluntary intake and apparent digestibility.

1. Thirty lactating British Friesian heifers and cows were individually given maize silage ad libitum containing 331 g dry matter/kg, 13 g nitrogen and 11·2 MJ of metabolizable energy per kg dry matter. Urea or aqueous ammonia was mixed in at the time of feeding to give 7·0 g nitrogen per kg silage dry matter. Urea-treated silage was given with concentrates at a high (mean 6·6 kg dry matter/day: treatment HU) or a low (mean 3·3 kg:treatment LU) level of feeding; the lower level only was given with ammonia-treated silage (treatment LA).

2. The addition of ammonia raised silage pH values from 3·9 to 4·4. Silage dry-matter intakes in lactation weeks 7 to 22 for treatments HU, LU and LA were 8·8, 11·1 and 10·7 kg/day.

3. Digestible organic matter content in the dry matter of the diets measured in vivo was not significantly affected by treatment. However, digestible organic matter intakes were significantly greater for treatment HU than for LU in weeks 7 to 10, and for LU than for LA in weeks 11 to 22.

4. The yields of milk and the contents of protein, lactose and energy did not differ between treatments. The milk yields for treatments HU, LU and LA in weeks 7 to 22 were 20·2,19·2, 18·8 kg/day respectively. Fat content of milk was significantly depressed with the HU treatment for heifers in weeks 7 to 10. The live-weight changes of the cows in weeks 7 to 22 for treatments HU, LU and LA were +0·10, −0·07 and −0·37 kg/day; the live-weight loss by cows given treatment LA was significantly greater than for LU. The live-weight change of the heifers was not affected by treatment.

Responses of gross energy intake and body weight of mice from weaning to maturity to dietary composition of energy-yielding nutrients were studied. Twenty-four groups of ddY male mice were fed for 70 days purified diets with a range of 0·08 to 0·75 protein, 0 to 0·92 fat and 0 to 0·92 carbohydrate concentration, calculated on a gross energy basis. Food intake and body weight data in each group were analysed by non-linear regression to obtain values of the parameters in the feeding and growth equation of Parks (1982). Prediction equations for these parameters were obtained with mixture model forms as a function of dietary protein, fat and carbohydrate. These equations for the parameters were then used to construct the response surfaces of body weight and growth rate at a given time on a triangular graph. The response surfaces of body weight at any time were convex, peak positions of which shifted from 043 protein and 0·29 fat at 10 days to 0·36 protein and 0·52 fat at 70 days. The configuration of response surfaces of growth rate (dW/dt) to the three components depends on feeding periods and at the longer periods of feeding the convex configuration of the surfaces became planar. The response surfaces of food efficiency (dW/dF) at any age were almost parallel to those of dW/dt, whereas a parallelism was observed between response surfaces of dW/dt and dF/dt only in young animals. These results suggested that the responses of body weight in young animals to dietary composition of energy-yielding nutrients depended on those of daily energy intake as well as food efficiency, but that those in older animals were affected by food efficiency only.

Haemoglobin and potassium types were related to body weights from birth to 1 year of age and first 6-monthly wool yield in the Nali breed of Indian sheep. Weighted mean comparisons between haemoglobin and potassium types made within sires for weights at birth, weaning (3 months), 6 months and 1 year and first 6-monthly wool yield did not show any statistically significant differences for any of these traits.

Fifty-six young female Suffolk × (Cadzow Improver × Scottish Blackface) sheep were used in a 2 × 2 × 2 factorial experiment investigating: (i) change in daylength (constant C v. reduced R), (ii) level of feeding (to appetite, H, v. 75% of that allowance, L), and (iii) age at hormone treatment (20 v. 28 weeks). At the appropriate age, the sheep were treated with a progestagen (MAP) and 750 i.u. PMS, inseminated, and slaughtered 26 days later. In a second experiment, change in daylength and level of feeding only were investigated. Hormone treatment took place at 20 weeks of age. In both years, all sheep showed oestrous behaviour and ovulated. A greater number of sheep yielded embryos on C than on R treatments (P<0·05 in Year 2), but no effect of feed level or age was found. Of those sheep not yielding embryos, a greater number on R than on C treatments showed a second ovulation at 20 weeks but not at 28 weeks.

The sense of bitter taste is critical for chickens to acquire and select feeds. It is important to understand the roles and mechanisms of bitter taste transduction in chickens. Denatonium is extensively used as a bitter taste receptor agonist to activate bitter taste receptors in recent studies. The objective of this study was to investigate the physiological effects and the potential molecular mechanisms of dietary exposure to a strong bitter taste receptor agonist on the jejunal epithelial cells of yellow-feathered chickens. A total of 240 yellow-feathered chickens were divided into four treatments receiving a normal diet (Control), a low-dose denatonium treatment (Control + 5 mg/kg denatonium), a middle-dose denatonium treatment (Control + 20 mg/kg denatonium) and a high-dose denatonium treatment (Control + 100 mg/kg denatonium) for 56 days, respectively. The results showed that dietary denatonium reduced (P < 0.05) the growth performance of chickens. High-dose denatonium damaged the morphology of the jejunal epithelium and decreased (P < 0.05) the activities of Ca2+-ATPase, sucrase and maltase after 56 days of exposure. Meanwhile, high-dose denatonium increased (P < 0.05) mRNA expressions of bitter taste receptors, which resulted in enhanced apoptosis in jejunal epithelial cells after 56 days of exposure. Furthermore, middle-dose and high-dose denatonium exhibited increased (P < 0.05) mRNA level of claudin 2 and decreased (P < 0.05) mRNA level of occludin after 28 days of exposure. Only high-dose denatonium decreased (P < 0.05) mRNA level of occludin after 56 days of exposure. In conclusion, denatonium manifested deleterious effects on the jejunum of chickens in a dose–effect manner via damaging the morphology of the jejunal epithelium, and inducing apoptosis associated with bitter taste receptors. Our data suggest that bitter-tasting feed additives may have side effects on the growth and development of intestines in chickens.

Fleece characteristics of three distinct strains of Scottish Blackface sheep were studied by sampling eighteen ewes of the Lanark, Galloway and Lewis strains on three occasions in a single year. During the period of maximum growth the Lewis strain, which is largely of historical interest, differed significantly from the others in S/P ratio and mean weight, diameter and degree of medullation in fine and coarse fibres. The differences between the other two strains were small and although a considerable range in fleece characteristics was found, most of the whole fleeces would be classed as ‘medium’ wool.

All three strains showed a considerable reduction in follicle output during the winter and spring months when differences amongst them were minimised.

Sufficient amino acid (AA) transport is essential to ensure the normal physiological function and growth of growing animals. The processes of AA sensing and transport in humans and murine animals, but rarely in goats, have been arousing great interest recently. This study was conducted to investigate the messenger RNA expression patterns of lysophosphatidic acid receptor 5 (LPAR5), guanine nucleotide-binding protein α-transducing 3 (GNAT3) and important partial AA transporters in digestive tracts, metabolic organs and muscles of growing goats. The results showed that these genes were widely expressed in goats, and had different expression patterns. LPAR5, GNAT3, solute carrier (SLC38A2), SLC7A7, SLC7A1 and SLC3A1 were rarely expressed in the rumen, but were highly expressed in the abomasum and intestine which are the main sites of AA absorption. GNAT3, SLC38A1, SLC38A2, SLC6A19, SLC7A7 and SLC7A1 showed comparatively high expression in the pancreas and the vital digestive glands, and the relatively high expression of these nine genes were noted in the tibialis posterior, the active muscle in energy metabolism. The correlation analysis showed that there were certain positive correlation among most genes. The current results indicate that the AA sensing and transport occur extensively in the abomasum and small intestine, metabolic organs and muscle tissues of ruminants, and that related genes have tissue specificity.

Artificial insemination protocols depend on efficient behavioral estrus detection and insemination time in Angora goat. Therefore, we aim to determine the accuracy of an estrus scoring system in Angora goats with different PMSG doses during the breeding season. Does (n: 260) were randomly divided into three groups: group-1 (n: 93), group-2 (n: 85) and group-3 (n: 82). All animals received an intravaginal sponge on day 0 for 11 days, and on the day of sponge insertion 150 μg prostaglandin F2Α was administered. Pregnant mare’s serum gonadotropin was injected 300, 400 and 500 IU intramuscularly 24 h before sponge removal to groups 1, 2 and 3, respectively. Estrus signs were detected with a teaser buck, 24 h after sponge removal according to a visual scoring system. Artificial insemination was performed with 0.25 ml fresh diluted semen at 43 to 45 h after sponge removal. Differences were observed within PMSG groups in terms of standing, tail wagging, courtship behavior, vaginal discharge and vaginal hyperemia (P<0.001). Nevertheless, the most accurate indicators of estrus that result in pregnancy were tail wagging and courtship behavior followed by standing estrus (P<0.05). According to the results obtained, 300 IU PMSG dose is sufficient, both to inseminate at a fixed time (43 to 45 h after sponge removal) and to record the estrus behavior by teaser male 24 h after sponge removal. Higher PMSG doses (400 to 500 IU) altered the timing of ovulation; specifically, 500 IU dose shortened the duration of estrus behaviors. In conclusion, even though the different doses of PMSG displayed similar effects on estrus synchronization and pregnancy rates, we concluded that tail wagging, courtship behavior and standing heat are the most reliable estrus signs for artificial insemination in Angora goat.