Effects of insulin-like growth factor-I (IGF-I) infusion and dietary tri-iodothyronine (T3) supplementation on growth, body composition and plasma hormone levels in sex-linked dwarf mutant and normal chickens.

This study used a sex-linked dwarf mutant (SLD) chicken to evaluate growth-promoting and metabolic effects of recombinant human insulin-like growth factor-I (rhIGF-I) treatment. The SLD chicken is characterized by a 30% reduction in body weight and by high plasma GH levels, low plasma IGF-I and triodothyronine (T3) levels and very low GH binding on liver membranes, suggesting reduced functional GH receptors compared with normal chickens. The effects of a continuous s.c. infusion by osmotic mini-pump of 0.1 mg rhIGF-I/kg per day from 4 to 8 weeks of age on body weight, bone growth and body composition were investigated in female SLD and normal chicks. In addition, half of the birds received a dietary supplement of T3 (0.1 parts per million). Plasma levels of IGF-I, GH, T3, thyroxine and insulin were followed during the treatment. In normal chicks, rhIGF-I infusion had no effect on growth and little effect on plasma hormone levels except for a decrease in plasma insulin. In dwarf chicks, rhIGF-I infusion slightly increased body weight but had no effect on longitudinal bone growth. In addition, plasma GH levels were decreased and T3 levels remained lower than in normal chicks. Normal and dwarf chicks showed a decrease in abdominal fat after both IGF-I administration and T3 supplementation, the treatments having additive effects in dwarf chicks only. The combined rhIGF-I and T3 treatment restored a quasi-normal hormonal pattern in dwarf chicks, except for insulin which remained lower than in normal chicks. These results suggest that IGF-I in the chicken has no direct endocrine effect on statural growth.

Fearfulness and performance related traits in selected lines of Japanese quail (Coturnix japonica).

Fearfulness and economic traits were studied in three lines of Japanese quail. Two of the lines were of the same genetic origin and were subjected to divergent selection for the duration of tonic immobility (TI), a measure of fearfulness. Birds were selected for long (LTI) or short (STI) duration of TI. The third line (DD) was of a different genetic origin and had been selected for early egg production. Fear, growth, residual feed intake, and measures of egg composition and production varied among lines. The distribution of TI in Line DD was closer to that from Line STI. Residual feed intake and shell content were lowest in the DD line. The DD birds laid more broken eggs than quail of the other lines. The STI line birds had higher BW and laid more, but smaller, eggs than LTI line birds. Eggs laid by LTI line birds had higher albumen content, but lower percentage shell, than those laid by STI line birds. When all traits were considered together, there was an overall tendency for STI line birds to out perform LTI birds with DD line birds showing intermediate performance. This finding supports the notion that there is a relationship between fearfulness and productivity. However, the skewed distribution of TI precluded estimation of correlation with production traits in the LTI and STI lines. No significant relationships among fear and production-related traits were found in the DD line, which contradicts the notion that fearfulness and production are related.

Comparison of outbred lines of chickens for resistance to experimental infection with coccidiosis (Eimeria tenella).

Coccidiosis causes dramatic economic losses in the poultry industry. Next to the extensive use of anticoccidial drugs, improving genetic resistance of birds to this parasitic disease represents an attractive alternative. An experiment was run in order to identify lines of chickens resistant and susceptible to coccidiosis as a tool to search for genetic markers of resistance. Five outbred lines were used: two Egyptian lines (Mandarah and Fayoumi), a Rhode Island Red line, and two White Leghorn lines (WLB21 and WLDW). The WLDW line segregated for three MHC haplotypes, B15, B19, and B21, and for the sex-linked dwarf gene, DW. Chicks were challenged at 4 wk of age with a high dose of Eimeria tenella (150,000 oocysts) and slaughtered 8 d postinoculation. Innate resistance was assessed individually by measures of lesion score, mortality, and body weight gain at slaughter, and plasma coloration 4 d postinoculation. Large differences in resistance to E. tenella were observed between lines. The Fayoumi line appeared clearly as the most resistant line, showing no mortality, less severe lesions than other lines, and a 30% reduction of growth as compared to control birds. The WLDW line was the most susceptible, with 27% mortality and a 85% reduction in growth. No major effect of MHC or dwarfism on resistance to E. tenella was found.

Mapping of plumage colour and blood protein loci on the microsatellite linkage map of the Japanese quail.

The objective of this work was to map classical markers (plumage colours and blood proteins) on the microsatellite linkage map of the Japanese quail (Coturnix japonica). The segregation data on two plumage colours and three blood proteins were obtained from 25 three-generation families (193 F2 birds). Linkage analysis was carried out for these five classical markers and 80 microsatellite markers. A total of 15 linkage groups that included the five classical loci and 69 of the 80 microsatellite markers were constructed. Using the BLAST homology search against the chicken genome sequence, three quail linkage groups, QL8, QL10 and QL13, were suggested to be homologous to chicken chromosomes GGA9, GGA20 and GGA24, respectively. Two plumage colour loci, black at hatch (Bh) and yellow (Y), and the three blood protein loci, transferrin (Tf), haemoglobin (Hb-1) and prealbumin-1 (Pa-1), were assigned to CJA01, QL10, QL8, CJA14 and QL13, respectively.

Testing homology of loci for two plumage colors, "lavender" and "recessive white," with chicken and Japanese quail hybrids.

Homology for two plumage color loci was studied by hybridization between chickens and Japanese quail. First, chicken-quail hybrids were produced from homozygous "lavender" chicken cocks and "bleu" Japanese quail, and all 30 hybrids had the same parental slate blue plumage color. On the other hand, no hybrids with this plumage were obtained out of 18 progeny from the same cocks and wild-type quail. These results show that the slate blue plumage color is determined by homologous loci in Japanese quail and chickens. Second, all (n = 25) chicken-quail hybrids hatched from homozygous "recessive white" cocks and "recessive white" (n = 8) or "wild-type" (n = 17) quail had the same pattern of plumage color, with white feathers on the ventral face and colored feathers elsewhere. These results indicate that the recessive white mutations are not homologous in Japanese quail and chickens.

Long-term egg production and heterosis in quail lines after within-line or reciprocal recurrent selection for high early egg production.

1. Four Japanese quail lines were developed using 13 generations of reciprocal recurrent (lines AA and BB) or within-line selection (lines DD and EE) for high egg number until 98 d of age. In these lines and their reciprocal crosses, egg production, egg weight and mortality were monitored for up to 21 months to evaluate the impact of selection method and line origin on long-term production and heterosis. 2. Both hen-housed total egg number (EN) and hen-day egg laying rate (ELR) were consistently lower in recurrent lines than in lines under within-line selection: after 13 months of test, the difference was -47.1 eggs for EN and -20% for ELR%, whereas mortality was similar at around 20%. 3. Line EE was the best pure line for early egg production (55.2 eggs at 98 d of age) and also gave eggs which were consistently about 2 g larger than those from line DD but it had the highest overall mortality (78.5%) of all lines. On average, line DD laid 399 eggs (EN) over the whole experiment, 84 more than Line EE. 4. Crossbreds from the 2 types of pure lines and line DD had similar patterns and rates of egg production during the whole experiment, as indicated by the similarity of the curves adjusted for those lines by using the monomolecular model for EN and the modified compartmental model for ELR. 5. However, heterosis was higher from recurrent selection lines and it increased more with time than did heterosis from within-line selection lines.

Effects of two-locus combinations, using the roux, lavender, and beige mutations, on plumage color of Japanese quail.

The interactions between the effects of three plumage color mutations taken two-by-two (sex-linked recessive roux, autosomal recessive lavender, and autosomal dominant beige) were studied in Japanese quail by producing a total of 121 F(1) and 1118 F(2) quail from the three pure stocks. Three new plumage colors were obtained in F(2) quail: roux-diluted beige, cream, and lavender-diluted beige. Two of them, roux-diluted beige (from the roux and beige mutations) and cream (from the roux and lavender mutations) corresponded to double homozygotes or hemizygous birds, and could therefore be used to tag a quail line. On the other hand, an F(3) from F(2) birds with lavender-diluted beige plumage was necessary to show that quail with this plumage color were homozygous for the lavender mutation, but were either homozygous or heterozygous for the beige gene. In all three F(2)s, observed segregation of plumage colors fit simple two-locus Mendelian inheritance.

Effect of triiodothyronine supplementation on thyrotropin-releasing hormone-induced growth hormone secretion in sex-linked dwarf and normal chicks.

The effect of a dietary triiodothyronine (T3) supplement, of either 0.1 or 0.5 microgram/g of feed, was studied on the thyrotropin-releasing hormone (TRH)-induced growth hormone (GH) secretion in sex-linked dwarf (dw) or normal (Dw) chicks of both sexes. In normal chicks, 0.1 microgram/g T3 decreased plasma GH levels before TRH as well as the GH increase after TRH, and 0.5 microgram/g T3 totally suppressed any response to TRH, either at 4 or at 7 weeks of age. Dwarf chicks were more sensitive to TRH than normals when receiving either 0 or 0.1 microgram/g T3; 0.5 microgram/g T3 abolished the difference between genotypes at 4 weeks of age but not so clearly at 7 weeks of age, where dwarf females showed a slight but still significant GH increase after TRH. Interactions between genotype, TRH injection, and T3 treatments were often significant at 4 weeks of age and even more at 7 weeks of age. Dwarf chicks receiving 0.1 microgram/g T3, expected to have normal plasma T3 levels, showed a higher GH response after TRH. This suggests that other hormones may be involved in the regulation of this response, particularly IGF-I, which is known to remain at a low level in T3-treated dwarf chicks.

Societal synchronization in groups of rats or quail submitted to various lighting regimens.

Groups of rats or of quail that had been previously synchronized in a light (L = 100 lux) dark (D) phase opposition (PO = LD and DL) were placed together in a L12:D12 or D12:L12 alternation or in continuous light (LL) or continuous darkness (DD). Emission of carbon dioxide (VCO2) which was continuously recorded in groups of individuals placed in respiratory chambers under controlled environmental conditions allows an index of their overall respiratory and metabolic exchanges to be found. In PO animals placed in LD or DL, the VCO2 circadian light dark synchronization comes back less quickly in rats than in quail, and the VCO2 variations at the light dark transitions (L-D and D-L) remain unchanged in rats, but are modified in quail. When PO animals are placed for 18 days in LL or DD, respiratory circadian rhythms disappear except in the grouped rats where they reappear after 4-5 days in DD.

Effect of the sex-linked dwarf gene on circulating levels of 17 beta-estradiol, progesterone and luteinising hormone in the laying hen.

1. The sex-linked dwarf gene did not appear to affect the LH, progesterone (P4) and oestradiol 17-beta (E2) levels around the onset of lay in a sample of White Leghorn hens. 2. A longer interval between oviposition and subsequent ovulation was suggested in dwarf layers by a slower decrease in the P4 plasma concentration after the preovulatory peak and is consistent with the increased oviposition interval already described. 3. A higher ratio of E2/P4 basal levels was found in dwarf layers; this is consistent with their lower number of fast-growing follicles and with their reduced laying rate. 4. Lipid mobilisation was modified in dwarf layers (as shown by their reduced abdominal fattiness); although plasma concentrations of triglycerides were normal, unusual correlations between plasma triglycerides, E2 basal concentrations and body weight were recorded.

Genetic similarity and relationships of DNA fingerprints with performance and with heterosis in Japanese quail lines from two origins and under reciprocal recurrent or within-line selection for early egg production.

DNA fingerprints of Japanese quail male and female pure line breeders were obtained with probes 33.6, 33.15, and R18.1 and they yielded a total of 59 scoreable bands. Bandsharing (0

A first-generation microsatellite linkage map of the Japanese quail.

A linkage map of the Japanese quail (Coturnix japonica) genome was constructed based upon segregation analysis of 72 microsatellite loci in 433 F(2) progeny of 10 half-sib families obtained from a cross between two quail lines of different genetic origins. One line was selected for long duration of tonic immobility, a behavioural trait related to fearfulness, while the other was selected based on early egg production. Fifty-eight of the markers were resolved into 12 autosomal linkage groups and a Z chromosome-specific linkage group, while the remaining 14 markers were unlinked. The linkage groups range from 8 cM (two markers) to 206 cM (16 markers) and cover a total map distance of 576 cM with an average spacing of 10 cM between loci. Through comparative mapping with chicken (Gallus gallus) using orthologous markers, we were able to assign linkage groups CJA01, CJA02, CJA05, CJA06, CJA14 and CJA27 to chromosomes. This map, which is the first in quail based solely on microsatellites, is a major step towards the development of a quality molecular genetic map for this valuable species. It will provide an important framework for further genetic mapping and the identification of quantitative trait loci controlling egg production and fear-related behavioural traits in quail.