A theoretical equation is proposed which describes the dynamics of foetal growth in mice. The equation is basically of exponential form and takes into account the effects of stage of gestation (T) and number of foetuses (N) on the instantaneous relative growth rate. The model was tested against experimental data by using a stepwise regression technique. Both stage of gestation and number of foetuses had significant effects (P < 0·01) on the instantaneous growth rate. When the model was tested against another set of data 44 out of a total of 52 comparisons had a prediction error less than 15 %. As a result, the following equation is proposed to describe the foetal growth of mice

W = e-14·34Ne(1·302–0·0276T–0·00059)T

An equation of this form could be useful in interpreting prenatal growth data for other species. Other factors which may influence the dynamics of foetal growth, such as maternal age or weight, could also be incorporated into the equation.

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.

Insulin-like growth factor binding protein-5 (IGFBP-5) is a key molecule in mammary gland development, which facilitates the removal of mammary epithelial cells (MECs) by apoptosis that takes place during remodeling of the mammary gland during involution. IGFBP-5 binds with IGFs for their bioavailability. IGFBP-5 has been reported to perform pleiotropic roles such as cellular apoptosis, proliferation and differentiation. To understand the role of IGFBP-5 during lactation and clinical mastitis, expression profiling of IGFBP-5 at the protein level was performed in both indigenous cows (Bos indicus) and buffaloes (Bubalus bubalis) belonging to two different breeds – Sahiwal cows and Murrah buffaloes. Reverse-transcriptase PCR (RT-PCR) of IGFBP-5 mRNA confirmed its expression in milk somatic cells and MECs of Sahiwal cows. ELISA was performed for quantitative measurement of IGFBP-5 concentrations in milk during different days (0, 50, 100, 150, 200, 250 and 300) of lactation, during the involution period and in animals exhibiting short lactation and clinical mastitis. The highest concentration of IGFBP-5 in milk was observed during the involution period followed by colostrum, late and early lactation, respectively, in both cattle and buffaloes. No significant difference in the concentration of IGFBP-5 was observed during the first 150 days of lactation between cows and buffaloes. However, higher concentration of IGFBP-5 was observed in cows during late lactation (200 to 300 days) in comparison with buffaloes. To validate the ELISA data, quantitative real-time PCR was performed in MECs of Sahiwal cows. The relative mRNA abundance of IGFBP-5 was found to be significantly (P<0.05) higher on day 15 than between 50 and 150 days of lactation in case of Sahiwal cows. Highest mRNA expression of IGFBP-5 was observed around 300 days of lactation followed by 200 and 250 days (P<0.05), respectively. Murrah buffaloes showed low levels of IGFBP-5 protein in milk as compared with Sahiwal cows during lactation in ELISA. Animals having history of short lactation length (short lactating animals) showed higher levels of IGFBP-5 expression (at protein level) in comparison with normal lactating animals. We propose that higher level IGFBP-5 expression may have functional significance in lactation persistency. As a pro-apoptotic molecule, higher expression of IGFBP-5 was observed to be inversely related to lactation length and milk production.

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.

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

Twenty-five Californian does were mated and given pelleted diets of either 8(LE) or 10(HE) MJ/kg dry matter (ruminant metabolizable energy values) throughout gestation and lactation. Litter sizes were adjusted to six offspring per doe. Milk yield was estimated from the weight differences of the litters before and after suckling, when the opportunity for nursing was confined to once daily. The young rabbits were allowed access to either the LE or HE diets from 18 days of age. Weaning took place at 32 days of age when four rabbits from each doe grouP × pre-weaning diet were slaughtered. Diet had no effect on litter size or birth weight, but does on the LE diet had lower live weights post partum (P < 0·05). Dry-matter consumption by the does on the LE diet was greater than for the HE diet (P < 0·05) both during gestation and lactation, but calculated metabolizable energy intakes were lower during lactation. There were no statistically significant differences between treatments for milk yield or live-weight gain to weaning and dry-matter intakes of the young at weaning, but daily live-weight gain from fostering to 18 days of age was greater for litters of does fed the HE rather than the LE diet (P < 0·05). There were no statistically significant differences between diets for carcass traits at weaning.

After weaning, 32 rabbits were given either the LE or HE diet until 2 kg live weight when they were slaughtered. A post-weaning × pre-weaning diet interaction (P < 0·05) occurred for live weights of the rabbits at the start of the post-weaning trial (i.e. after a 10-day adaptation period) with LE: LE rabbits being lighter than other rabbits as a results of poor live-weight gains during the adaptation period. Live-weight gains to slaughter were greater for the pre-weaning LE diet (P < 0·05) and the post-weaning HE diet (P < 0·01), although dry-matter intakes of the HE diet were less (P < 0·05). Rabbits on the LE diet had greater empty gut weights (P < 0·05) and lighter livers (P < 0·05) at slaughter.

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 effect of erythrocyte glutathione status and breed on the susceptibility of adult female sheep to the haemolytic anaemia caused by the brassica anti-metabolite dimethyl disulphide (DMDS) was determined in a factorial experiment. Within each breed (Scottish Blackface or Finnish Landrace), six sheep of low glutathione status (<30 mg/100 ml red blood cells (RBC)) and six sheep of high glutathione status (>70 mg/100 ml RBC) were dosed twice daily with DMDS for 35 days (25 mmol per head per day). All sheep developed a classic haemolytic anaemia within 2 weeks of the start of DMDS dosing. Weekly haemoglobin concentrations and packed cell volume values were not affected by breed or glutathione status. Heinz body numbers rose to a higher maximum in low glutathione animals but were not affected by breed. The results call into question the relationship between total erythrocyte glutathione concentration and the resistance of erythrocytes to oxidative damage.

Three experiments were carried out to investigate the effect of different forage types on the performance of male British Friesian calves up to 6 months of age. Unwilted and wilted silages were compared in all experiments, and in experiment 1 hay was also compared with the two silages. All the forages were compared at different levels of concentrate supplementation ranging, in different experiments, from none to ad libitum.

Calves fed wilted silage consumed 490, 90 and 200g/kg more forage dry matter respectively than those fed unwilted silage in the three experiments but this extra intake was generally not reflected in an increased rate of gain. Hay which was of lower digestibility than silage gave significantly lower live-weight gain. Quantities of silage consumed at an early age were small, with a mean daily intake over the first five weeks of 0·13 kg dry matter. Concentrate reduced silage dry-matter intake by 0·49 kg/kg concentrate dry matter consumed. Estimated mean concentrate intake required to achieve a daily gain of 0·75 kg in 1- to 6-month-old calves with silage offered ad libitum was 0·83 kg dry matter.

During winter in southern Queensland, eight rusa deer stags aged 4 years were given ad libitum lucerne (Medicago sativa) hay and confined in individual metabolism pens for 26 days. Stags ate 2·04 kg dry matter (DM) per day and drank 6·4 kg water per day, while the drinking water: food DM ratio was 3·3 l/kg. In experiment 2, seven rusa stags were given ad libitum lucerne hay or oaten (Avena spp.) hay with or without barley grain supplementation (200 g/day) for 56 days (four periods). This experiment was conducted from 26 July to 19 September 2001, when the stags were exhibiting the behaviour characteristic of the rut. Rusa stags ate 1·19 and 1·17 kg DM per day of lucerne and oaten hay respectively. Rusa stags given oaten hay drank slightly more water than those that received lucerne hay (5·34 and 4·47 kg/day, respectively). The drinking water: food DM ratios were 3·81 and 4·67 kg/kg for lucerne and oaten hay, respectively. Barley grain supplementation (200 g/day) had no influence on total food or water intakes of the rusa stags.

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.

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.

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.

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.

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.

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.

A total of 52 ram lambs of different morphological types slaughtered at a comparable stage of body development (carcass weights = 19·5 (s.d. 3·10) kg) were used to study the variation in the relationship between muscle and bone development in the hind limb using multivariate techniques. Development of individual muscles was expressed relative to the weight of the major bone to which they are closest, considered here as their carrier bone.

Variability of muscle: bone ratios of individual muscles varied considerably from one muscle to another. The coefficient of variation (CV) ranging from 0·111 to 0·462 (average CV = 0·199). Relative to the same bone, the variability of muscle: bone ratios for each of the three anatomical regions of the hind limb was still important. This suggests that variability may be due to other factors besides muscle weight, such as bone shape.

The correlation between the various muscle: bone ratios was low in some cases. However, a significant association existed between muscle: bone ratios of individual muscles and the total muscle: bone ratio in the hind limb which indicated that some muscle: bone ratios can be used as indicators of muscling in the selection of meat animals such as m. semimembranosus/femm, m. gluteobiceps/femur, m. adductores/'femur and m. semitendinosus/femur.

The most discriminant variables of the population in multivariate analysis were m. soleus/tibia, m. extensor digitorium lateralis/tibia, m. quadmtus femoris/coxal, m. gemelli/coxal and m. vastus medialis/femur. It was also possible to distinguish the different morphological types of the different breeds by the values of the ratios between these variables.

In a review of the effects of protein nutrition on reproduction in dairy cattle, Ferguson and Chalupa (1989) expressed concern at the low conception rates to first insemination in high-producing dairy cows and suggested that a contributory factor may be an excess of rumen-degradable protein leading to toxic effects of ammonia and its metabolites on gametes and/or the embryo. More recently Elrod and Butler (1993) have provided data suggesting that degradable protein intakes which were 50% above the requirements for maximum microbial protein synthesis reduced embryo survival in dairy heifers. The objective of the present study was to investigate the effect in ewes of varying the amount of rumen degradable protein during the pre-ovulatory progesterone priming phase and the first four days thereafter on ovulation, fertilization, early in vivo and subsequent in vitro ovum development.

Low selection intensity due to few selection candidates available at any one time due to thinly spread year-round lambings in villages and prohibitively large nucleus requirements to provide sufficient improved rams to the production tier are the major challenges for designing effective village-based and central nucleus-based breeding programmes, respectively, for smallholder sheep farmers. To tackle these challenges, we used deterministic simulation to design three schemes in village-based programmes introducing hormonal oestrus synchronization (natural oestrus (VNE), single oestrus synchronization (VSE1) and double oestrus synchronization (VSE2)) and three schemes in central nucleus programme introducing artificial insemination (AI) (natural mating with nucleus sizes of 5% (CNM1) and 1% (CNM2) of the total ewe population and natural mating in breeding tier and AI in production tier (CAI)). The schemes were evaluated for their bio-economic and operational feasibility, taking Bonga sheep of Ethiopia as a case study. The selection intensities achieved in VNE, VSE1 and VSE2 were 2.0, 2.3 and 2.4, respectively, for selecting rams for the breeding tier and 0.0, 0.8 and 1.0, respectively, for the production tier. The profits per ewe per year from VNE, VSE1 and VSE2 were Birr 12.2, 21.7 and 24.5, but the profit from VNE for the production tier was zero. CAI generated more genetic gains in the breeding objective (Birr 4.8) than CNM1 (Birr 2.5) and CNM2 (Birr 0.0) in the production tier. However, CAI was less profitable than CNM1 and CNM2. In conclusion, hormonal oestrus synchronization was found to be a feasible technological aide to accelerate genetic progress in village-based programmes. CNM1 and CNM2 could not be recommended as CNM1 requires large nucleus of 10 325 ewes and CNM2 results in zero genetic gain in the production tier. CAI could overcome the challenge in central nucleus programmes, namely unaffordable large nucleus, but the scheme needs to be subsidized by the public sector to be economically feasible for farmers.

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.