ABSTRACT
There are no studies regarding the estimation of genetic parameters and genetic trends for reproductive traits and somatic cells in goats. Their knowledge allows optimization of selection schemes. The objective of this study was to estimate genetic parameters and genetic and phenotypic trends for age at first kidding (AFK), kidding interval (KIN) and somatic cell score (SCS). Analyses were conducted within and across seven US goat breeds, namely, Nubian (NU), Alpine (AL), LaMancha (LM), Toggenburg (TO), Saanen (SA), Nigerian Dwarf (ND) and Oberhasli (OB), and a set of all of these breeds (AB). The restricted maximum likelihood methodology and trivariate animal models were used. Genetic and phenotypic trends were estimated using regression models. The average and standard deviation of AFK, KIN and SCS for AB were 573.6 ± 178.5 days, 418.8 ± 125.5 days and 4.67 ± 2.23 Log2, respectively. The heritabilities (h2) and standard errors of AFK, KIN and SCS for AB were 0.28 ± 0.02, 0.04 ± 0.02 and 0.22 ± 0.01, respectively. The h2 ranged from 0.15 (SA) to 0.37 (NU) for AFK, from 0.04 (AB) to 0.10 (AL) for KIN, and from 0.11 (TO) to 0.26 (LM and ND) for SCS. Genetic correlations between AFK and KIN and between AFK and SCS for AB were positive and weak (0.07 and 0.12, respectively) but significant (P < 0.01). Genetic correlations between SCS and KIN were significant (P < 0.01) for all the breeds and ranged from -0.15 (NU) to 0.44 (AL). Genetic correlations between AFK and SCS in the NU and AL breeds were similar (approximately 0.21). A positive genetic trend was found for KIN in the SA breed, which caused an increase in the number of days between consecutive kiddings. The genetic trend of SCS for the NU, AL and ND breeds was negative and decreased annually, which is beneficial for producers. These first results show the intensity and direction of some favorable/unfavorable relationships between AFK or KIN and SCS Log2 in some U.S. goat genetic groups.
Subject(s)
Goats , Reproduction , Animals , Goats/genetics , Female , Breeding , Phenotype , United States , Male , DairyingABSTRACT
Media formulated with insect cuticle (0.5% and 1%; Sphequit Sph®), with a reduction in nutrients (» Sabouraud dextrose agar + yeast [SDAY]) and commercial media (potato dextrose agar, Sabouraud dextrose agar) were evaluated for the cultivation of Beauveria bassiana, Cordyceps javanica (Isaria javanica [Bally] Samson & Hywel-Jones), and Metarhizium robertsii. By using principal component analysis, it was determined that the » SDAY and Sph formulations have greater advantages than commercial media for the development of fungi. The » SDAY and Sph (0.5% and 1%) improved hydrophobicity, radial growth rate, germination, conidia yield, and virulence in B. bassiana; in M. robertsii, they favored conidia yield, germination, and virulence, and in C. javanica, the » SDAY and Sph 0.5% media enhanced conidia yield, germination, radial growth rate, and virulence. We suggest that these formulations are an alternative to commercial culture media as they are cheaper and appropriate to improve the growth characteristics and virulence of the three strains evaluated. Some applications of culture media are suggested, and the importance of multivariate analysis as an exploratory tool to carry out the choice of culture media in a suitable way for the development of mycoinsecticides is also discussed.
