Effect of cycling temperature on growth, energy metabolism and nutrient retention of individual male turkeys.

1. Each week, from 12 to 20 weeks of age, male turkeys of a heavy strain were subjected to cool (C; 16 degrees C), hot (H; 29 degrees C), and cycling temperatures, and fed on a standard diet ad libitum for 4 d. Lighting was intermittent, 3 h on, 3 h off.

Mapping of the pig genome.

The past year has seen major developments in both the genetic (linkage) and physical maps of the porcine genome. Landmark loci have been established on all pig chromosomes and outline genetic maps have been elaborated. The use of pigs as models of human genetic diseases is likely to expand through the use of transgenic pigs.

Alterations in glycosaminoglycan concentration and sulfation during chondrocyte maturation.

We have used antibodies to chondroitin 4- and 6-sulfate and keratan sulfate along with Alcian blue staining of sulfated proteoglycans to investigate changes in content and sulfation within the avian growth plate. In normal chicks, chondroitin 4- and 6-sulfate content were similar in the proliferating and transitional zones but in the hypertrophic zone, chondroitin 4- and 6-sulfate were slightly lower (13% and 18%, respectively) and keratan sulfate was markedly lower (58%). Compared with the proliferative zone, Alcian blue staining of sulfated glycosaminoglycans was markedly lower in both the transitional (46%) and hypertrophic (22%) zones.

Insulin-like growth factor-I in the ovary of the laying hen: gene expression and biological actions on granulosa and thecal cells.

Concentrations of insulin-like growth factor-I (IGF-I) were measured in granulosa and thecal tissue dissected from the three largest follicles in the ovaries of laying hens. The higher concentration was found in extracts of granulosa (0.82 +/- 0.

Type II collagen expression in small, biopsy-sized samples of cartilage using a new method of RNA extraction.

The extraction of mRNA from cartilage samples is complicated by the presence of proteoglycans and the low cellular density of the tissue. We required a method that would enable mRNA to be extracted from small biopsy-sized samples of cartilage. The method had to produce consistent results and sufficient RNA for Northern and PCR analysis.

Type-I insulin-like growth factor receptor gene expression in the chick. Developmental changes and the effect of selection for increased growth on the amount of receptor mRNA.

An RNase protection assay is described that allowed the quantitative analysis of chicken type-I IGF receptor mRNA transcripts. The transcripts were measured in extracts of total nucleic acid (TNA) and, under the hybridization conditions described, protected probes of the expected size were obtained. The RNA-RNA hybrids could be quantified in the presence of at least a 1000-fold molar excess of DNA containing sequences which were complimentary to the RNA probe.

Calculation of prediction error variances using sparse matrix methods.

The use of exact and approximate algorithms to calculate prediction error variances using sparse matrix methods are demonstrated for an individual animal effect including maternal effects. One exact algorithm is substantially faster than two others. An approximation of the best exact method gave an acceptable level of reliabilities and reduced the computation by a factor of approximately fifty compared with the exact computation and is routine in national beef evaluation in Britain.

Control of cleavage and further development in vitro in reconstituted two-cell mouse embryos.

Nuclear-cytoplasmic interactions during the second cell cycle of mouse embryos were examined by assessing the timing of cleavage in reconstituted two-cell embryos and their ability to develop further to the blastocyst stage in vitro. Nuclear transplantations were performed either within or across the cell cycle and at different stages of the cell cycle to assess the effect of 'asynchrony' on development. In most cases, cleavage occurred at an intermediate time between nuclear and cytoplasmic controls indicating an interaction in their mechanisms for controlling the timing of cleavage.

The effect of LH, FSH and pregnant mares' serum gonadotrophin on ornithine decarboxylase activity in thecal and granulosa tissue during follicular growth and atresia in laying hens (Gallus domesticus).

The effect of ovine LH, porcine FSH and pregnant mares' serum gonadotrophin (PMSG) on the activity of ornithine decarboxylase activity in theca and granulosa tissue during folliculogenesis in laying hens is described. The changes in the activity of ornithine decarboxylase induced by hormonal challenge was used to measure the sensitivity of the tissue to the hormone. Thecal tissue from small (< 6 mm) follicles showed a large increase in the activity of ornithine decarboxylase 3 h after treatment with LH, FSH and PMSG, in vivo, whereas ornithine decarboxylase activity in thecal tissue from large (> 8 mm) preovulatory follicles and atretic follicles did not respond to any of the hormonal treatments.

Rapidly growing broiler (meat-type) chickens: their origin and use for comparative studies of the regulation of growth.

1. Rapidly growing (meat-type) chickens have been intensively selected for over 50 years and grow up to four times faster than "layer" strains selected for reproductive traits. 2.

Altered localisation of transforming growth factor-beta 3 during endochondral ossification in rachitic chicks.

Growth plates from chicks displaying hypocalcaemic rickets, hypophosphataemic rickets and dyschondroplasia were studied. Immunohistochemical staining using specific TGF-beta 3 antibodies showed disruption of TGF-beta 3 localisation in all three disorders. In hypocalcaemic rickets, transitional and hypertrophic chondrocytes showed expression of TGF-beta 3, while accumulating, proliferative chondrocytes showed little expression.

Transgenic birds by DNA microinjection.

We have developed a method for production of transgenic chickens by DNA microinjection of chick zygotes followed by ex vivo embryo culture. The fate of plasmid DNA microinjected into the germinal disc of zygotes was analyzed in embryos which survived for at least 12 days in culture. Approximately half of the embryos contained plasmid DNA, 6% at a level equivalent to one copy per cell in all tissues analyzed.

1D-IEF analysis of BoLA class I expression using allo-antisera reveals additional complexity.

The use of the bovine allo-antisera in lymphocyte microcytotoxicity assays suggests that there is a single highly polymorphic class I product expressed by the BoLA system encoded by one locus. In contrast, biochemical techniques, such as 1D-IEF, reveal a complex pattern of bands for BoLA class I molecules from each animal. In order to understand the origins of this heterogeneity bovine allo-antisera were used in the immunoprecipitation step of 1D-IEF and the results compared with those from immunoprecipitation using the monoclonal antibody W6/32.

Effects of recombinant bovine somatotrophin, insulin-like growth factor-I and insulin on the proliferation of bovine granulosa cells in vitro.

Treatment of heifers with recombinant bovine somatotrophin (BST) significantly increases the population of small ovarian follicles and peripheral concentrations of somatotrophin, insulin-like growth factor-I (IGF-I) and insulin. To investigate the possible mechanism(s) involved in the action of BST on ovarian follicles, the effects of BST, IGF-I and insulin, given alone or in combination with either FSH or LH, on the proliferation of bovine granulosa cells in vitro were examined using a serum-free culture system. Bovine granulosa cells were obtained from antral follicles classified into three size categories according to diameter: small < 5 mm; medium-sized 5-10 mm and large > 10 mm.

Effects of long-term food restriction on energy expenditure and thermoregulation in broiler-breeder fowls (Gallus domesticus).

1. From 2 to 21 weeks of age, 150 female broiler-breeder chicks received one of three dietary treatments. Fifty received an ad libitum supply of food (treatment AL).

Characterization of the chicken preprogonadotrophin-releasing hormone-I gene.

Partial cDNA clones for chicken gonadotrophin-releasing hormone (GnRH)-I were isolated by reverse transcription-polymerase chain reaction using total RNA from the hypothalami of domestic chickens. Primers for amplification were based on the nucleotide sequence of the mammalian GnRH genes. These amplified clones were used to screen a genomic library from which a series of overlapping clones was isolated.

Defective Down syndrome in chicks is not caused by riboflavin deficiency in breeders.

1. Riboflavin-deficient practical and semi-purified diets were fed to broiler breeder hens. 2.

The relationship between yolk cholesterol and total lipid concentration throughout the first year of egg production in the domestic fowl.

1. Variation of egg yolk cholesterol and total lipid concentration (mg/g wet yolk) throughout the first year of egg production for the domestic fowl is described. 2.

Importance of optimal mixtures of EDTA anticoagulant:blood for the preparation of well-stained avian blood smears.

1. This paper describes and illustrates the dangers of sub-optimal mixtures of EDTA anticoagulant:blood during the preparation of avian blood smears. 2.

Influence of degree of food restriction, age and time of day on behaviour of broiler breeder chickens.

Six groups of 25 growing female broiler breeder chickens in pens were fed either on a commercial restricted ration (R), twice that amount (2R), or ad libitum (AL). R and 2R birds were fed daily at 09.00 h and ate all their food in < 15 min.

Proximal femoral degeneration in growing broiler fowl.

The pathologies in proximal femora of broilers with lameness attributed to disorders of the proximal femur, including so-called 'femoral head necrosis', are described. Samples were collected from a variety of flocks, farms and production systems. Ten 'normal' broilers were also examined.