Prolificacy and Its Relationship with Age, Body Weight, Parity, Previous Litter Size and Body Linear Type Traits in Meat-type Goats.

Data on age and body weight at breeding, parity, previous litter size, days open and some descriptive body linear traits from 389 meat-type, prolific Black Bengal goats in Tripura State of India, were collected for 3 and 1/2 years (2007 to 2010) and analyzed using logistic regression model. The objectives of the study were i) to evaluate the effect of age and body weight at breeding, parity, previous litter size and days open on litter size of does; and ii) to investigate if body linear type traits influenced litter size in meat-type, prolific goats. The incidence of 68.39% multiple births with a prolificacy rate of 175.07% was recorded. Higher age (>2.69 year), higher parity order (>2.31), more body weight at breeding (>20.5 kg) and larger previous litter size (>1.65) showed an increase likelihood of multiple litter size when compared to single litter size. There was a strong, positive relationship between litter size and various body linear type traits like neck length (>22.78 cm), body length (>54.86 cm), withers height (>48.85 cm), croup height (>50.67 cm), distance between tuber coxae bones (>11.38 cm) and distance between tuber ischii bones (>4.56 cm) for discriminating the goats bearing multiple fetuses from those bearing a single fetus.

Endocrine markers for identifying prolificacy potential and predicting fetal number in goats.

Identifying prolificacy potential and determination of fetal number during pregnancy for proper care and management of the pregnant goats bearing multiple fetuses and achieving the benefits out of multiple births are essential for sustainable goat farming. Our objectives were (1) to examine prolificacy potential in goats by using pituitary response to gonadotrophin releasing hormone (GnRH) challenge test, (2) to investigate hormonal profiles for the prediction of fetal number in pregnant goats and (3) to find out the most reliable timing of blood sampling for discriminating prolificacy trait and differentiating the goats bearing single, twin and triplet fetuses. In first experiment (GnRH challenge test), plasma FSH concentrations were significantly higher (P<0.01) among the goats belonging to triplet vs. twin vs. single kidding size groups after GnRH administration. Multivariate stepwise discriminant function analysis recognized that one blood sampling at 220min after GnRH administration can be used to distinguish prolificacy potential in goats. In second experiment, plasma progesterone levels were significantly higher (P<0.01) in goats bearing triplet vs. twin vs. single fetus between day 84 and 21 prior to parturition. Plasma estrone sulphate concentrations were found to be higher (P<0.05) in does bearing multiple fetuses than the does bearing single fetus between day 126 and 28 prior to parturition. A single blood sampling at day 63 prior to parturition was the most probable suitable time for discriminating kidding size by using plasma progesterone as marker.

Polymorphism of fecundity genes (FecB, FecX, and FecG) in the Indian Bonpala sheep.

The present study was designed for screening polymorphism of known fecundity genes in prolific Indian Bonpala sheep. Employing tetra-primer amplification refractory mutation system PCR, 11-point mutations of BMP1B, BMP15, and GDF9 genes of 97 Bonpala ewes were genotyped. The FecB locus of the BMPR1B gene and two loci (G1 and G4) of GDF9 gene were found to be polymorphic. In FecB locus, three genotypes, namely, wild type (Fec++, 0.02), heterozygous (FecB+, 0.23), and mutant (FecBB, 0.75) were detected. At G1 locus of GDF9 gene, three genotypes, namely, wild type (GG, 0.89), heterozygous (GA, 0.10), and mutant (AA, 0.01) were detected. At G4 locus of GDF9 gene, three genotypes, namely, wild type (AA, 0.01), heterozygous (AG, 0.14), and mutant (GG, 0.85) were detected. Statistically no significant correlation of polymorphism of FecB, G1, and G4 loci and litter size was found in this breed. All five loci of BMP15 and three loci of GDF 9 genes were monomorphic. This study reports Bonpala sheep as the first sheep breed where concurrent polymorphism at three important loci (FecB, G1, and G4) of two different fecundity genes (BMPR1B and GDF9) has been found.

Polymorphism of BMPR1B, BMP15 and GDF9 fecundity genes in prolific Garole sheep.

Mutation studies in different prolific sheep breeds have shown that the transforming growth factor beta super family ligands viz. the growth differentiation factor 9 (GDF9/FecG), bone morphogenetic protein 15 (BMP15/FecX) and associated type I receptors, bone morphogenetic protein receptor (BMPR1B/FecB), are major determinant of ovulation rate and consequent increase in litter size. The Garole sheep is a highly prolific sheep breed of India. Characterization of fecundity genes in these animals could substantially improvise the breeding programme in these animals as well as other sheep breeds of the region. The present study was therefore designed with the objective of polymorphism study of fecundity genes in these prolific microsheep. A total of 11 point mutations were detected by polymerase chain reaction (PCR)-based method. A competitive technique called tetra-primer amplification refractory mutation system-PCR was adapted to type a total of ten points of two ovine fecundity genes (GDF9 and BMP15). The FecB locus of the BMPR1B gene and G1 locus of GDF9 gene were found to be polymorphic. In FecB locus, two genotypes, wild type (FecB(+)) and mutant (FecBB), were detected with allele frequencies of 0.39 and 0.61, respectively. At G1 locus, two genotypes, mutant (A) and wild types (G) were detected with allele frequencies of 0.18 and 0.82, respectively. This study reports Garole sheep as the fourth sheep breed after Belclare/Cambridge, Lacaune and Small-tailed Han sheep, where coexisting polymorphism has been found in two different fecundity genes (BMPRIB and GDF9 genes).