Publications

The present study suggests the existence of an association between milk production traits and genetic polymorphisms at the growth hormone (GH) gene in the Portuguese indigenous Serrana goat. The DNA from 229 animals of two ecotypes (Jarmelista and Ribatejano) was analysed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique revealing a high degree of genetic polymorphism at the goat GH (gGH) gene. Two conformation patterns were detected in exons 1 and 2, 6 in exon 3, 10 in exon 4 and 5 in exon 5. The evaluation of an association effect between these SSCP patterns with milk, fat and protein yields and fat and protein percentages suggests a positive effect of pattern A/B of exon 4 for Ribatejano ecotype and of pattern A/B of exon 2 for Jarmelista ecotype with milk yield (P<0.05) and of pattern A/B of exon 1 and pattern B/B of exon 2 with protein percentage (P<0.05) for Ribatejano ecotype. The results support the hints suggested by previous studies of the importance of the gGH gene as a candidate gene for marker-assisted selection in goat breeds and suggest that exon 4 is a preferential target for further investigation on mutations that influence milk yield variation.

The present study suggests the existence of an association between milk production traits and genetic polymorphisms at the growth hormone (GH) gene in the Portuguese indigenous Serrana goat. The DNA from 229 animals of two ecotypes (Jarmelista and Ribatejano) was analysed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique revealing a high degree of genetic polymorphism at the goat GH (gGH) gene. Two conformation patterns were detected in exons 1 and 2, 6 in exon 3, 10 in exon 4 and 5 in exon 5. The evaluation of an association effect between these SSCP patterns with milk, fat and protein yields and fat and protein percentages suggests a positive effect of pattern A/B of exon 4 for Ribatejano ecotype and of pattern A/B of exon 2 for Jarmelista ecotype with milk yield (P<0.05) and of pattern A/B of exon 1 and pattern B/B of exon 2 with protein percentage (P<0.05) for Ribatejano ecotype. The results support the hints suggested by previous studies of the importance of the gGH gene as a candidate gene for marker-assisted selection in goat breeds and suggest that exon 4 is a preferential target for further investigation on mutations that influence milk yield variation.

The study was to determine the prevalent diseases of three native Nigeria goat breeds reared in the same environment for a period of 5 years (1995–1999). The indigenous goat breeds used were the Red Sokoto (RS), West African Dwarf (WAD) and their crossbreeds (CB). The prevalent diagnoses included mange, tick and flea infestations, helminthiasis, pneumonia, peste des petits ruminants (PPR), orf, abortion/stillbirth and premature delivery. Only the WAD had prevalence of helminthiasis, orf and premature delivery. The CB group had greater prevalence (P<0.05) of tick and flea infestations and of abortion/stillbirth than the other breeds. Age group had no influence on the prevalence of most of the diagnosed diseases. The kids were the major age group affected by orf. Seasonal variation in disease prevalence also was observed with mange and helminthiasis occurring during early- and late-rainy seasons. Seasons and genotype are therefore important factors affecting the prevalence and susceptibility of goats to diseases in the equatorial zone of southeastern Nigeria.

The study was to determine the prevalent diseases of three native Nigeria goat breeds reared in the same environment for a period of 5 years (1995–1999). The indigenous goat breeds used were the Red Sokoto (RS), West African Dwarf (WAD) and their crossbreeds (CB). The prevalent diagnoses included mange, tick and flea infestations, helminthiasis, pneumonia, peste des petits ruminants (PPR), orf, abortion/stillbirth and premature delivery. Only the WAD had prevalence of helminthiasis, orf and premature delivery. The CB group had greater prevalence (P<0.05) of tick and flea infestations and of abortion/stillbirth than the other breeds. Age group had no influence on the prevalence of most of the diagnosed diseases. The kids were the major age group affected by orf. Seasonal variation in disease prevalence also was observed with mange and helminthiasis occurring during early- and late-rainy seasons. Seasons and genotype are therefore important factors affecting the prevalence and susceptibility of goats to diseases in the equatorial zone of southeastern Nigeria.

Data from 19 feeding trials conducted on growing sheep from different institutes across India were subjected to regression analysis to derive requirements of TDN, CP and DCP for maintenance and body weight gain. Maintenance requirements for TDN, CP and DCP were 37.0, 6.68 and 4.43g/kg W0.75, respectively for the BW range of 7–15kg, and the corresponding maintenance requirements for the BW range of 15.1–30kg were 35.3, 6.98 and 4.49g. The corresponding requirements for 1g gain in BW were 0.91, 0.47, and 0.31g, for 7–15kg BW and 1.21, 0.43 and 0.30g, respectively for 15–30kg BW range. Regression equations had high R2 values (0.59–0.84) and the equations (F value) as well as coefficients were highly significant (P<0.001). Regressed values were used to develop feeding standards. Derived values matched well with the actual intake versus performance of animals under diverse feeding conditions. The new standards so derived predicted requirements and intake of nutrients for different production levels better than existing feeding standards; as these are based on a more thorough analysis of a larger database, the new feeding standards will be appropriate for wide use in India.

Data from 19 feeding trials conducted on growing sheep from different institutes across India were subjected to regression analysis to derive requirements of TDN, CP and DCP for maintenance and body weight gain. Maintenance requirements for TDN, CP and DCP were 37.0, 6.68 and 4.43g/kg W0.75, respectively for the BW range of 7–15kg, and the corresponding maintenance requirements for the BW range of 15.1–30kg were 35.3, 6.98 and 4.49g. The corresponding requirements for 1g gain in BW were 0.91, 0.47, and 0.31g, for 7–15kg BW and 1.21, 0.43 and 0.30g, respectively for 15–30kg BW range. Regression equations had high R2 values (0.59–0.84) and the equations (F value) as well as coefficients were highly significant (P<0.001). Regressed values were used to develop feeding standards. Derived values matched well with the actual intake versus performance of animals under diverse feeding conditions. The new standards so derived predicted requirements and intake of nutrients for different production levels better than existing feeding standards; as these are based on a more thorough analysis of a larger database, the new feeding standards will be appropriate for wide use in India.

Breeding objectives were developed for meat sheep in smallholder production circumstances in the tropics. The traits considered were litter size, lambing frequency, pre-weaning, and post-weaning lamb survival to 12 months, ewe survival, lamb live weight at 12-month, mature ewe live weight, consumable meat, kg of manure DM sold per ewe per year and residual DM feed intake. Three evaluation situations were considered: (i) base with constant number of ewes, (ii) fixed feed resource and (iii) setting feed costs to zero. Sensitivity analysis of economic values to price levels of inputs and meat production was carried out. The fixed feed resource situation appropriately describes smallholder production circumstances. In the base situation, meat production accounted for about 88% of revenue and manure the remaining 12%. Variable costs represented about 95% of the total cost. For the fixed feed resource situation, economic values (US$ per ewe per year) were 12.94 for litter size, 10.18 for lambing frequency, 0.19 for pre-weaning lamb survival, 0.24 for post-weaning lamb survival, 0.36 for ewe survival, 1.02 for 12-month lamb live weight, 0.14 for mature ewe live weight, 0.51 for consumable meat, 0.08 for kg of manure DM sold (per ewe per year) and -0.04 for residual DM feed intake. Litter size and lambing frequency were the most important traits in a breeding objective for smallholder production. Relative to the base situation, setting feed costs to zero had similar results as the situation with restricted feed resource but resulted in larger differences. Sensitivity analysis of economic weights to changes in prices and production circumstances indicated that future economic values for traits might change dependent on levels of output and prices. The exceptions, with regard to changes in meat price are kg of manure DM sold per ewe per year and residual DM feed intake, and with regard to feed costs are consumable meat and kg of manure DM sold per ewe per year. Economic values for 12-month lamb live weight, mature ewe live weight, consumable meat, kg of manure DM sold per ewe per year and residual DM feed intake were not sensitive to changes in management and marketing circumstances. Caution is recommended when the breeding objectives presented here are applied not to disadvantage smallholders in poor climatic years, when farmers are at their most vulnerable situation.