The Canchim beef cattle (5/8 Charolais + 3/8 Zebu) has been selected for meat production in Brazil since late 1950. In the present work the effects of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) polymorphisms were investigated in 688 animals born between 1998 and 2000. These animals belonged to two genetic groups, i.e., traditional and new lineages. Genotype effects on expected breeding values for birth weight (BW), weaning weight (WW) and yearling weight (YW) were investigated by the least square method. Significant effects were found for GH genotype on YW (p ≤ 0.05), with positive effects associated with the LV (leucine/valine) genotype. For IGF-1 genotypes, significant effects were found on BW (p ≤ 0.01) and YW (p ≤ 0.01). Average substitution effects for IGF-1 alleles estimated by regression analysis suggested a positive effect of the IGF-1 225 bp allele on BW and of the 229 bp allele on YW.

Records of 192 Hard henu cattle pertaining to first lactation traits over a period of 6years from 2008 to 2014were collected from history cum pedigree sheets maintained at Cattle breeding farm, Department of Animal Genetics and Breeding Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar. Data were analysed by LSML(Harvey, 1990) using mixed linear model having effect of sire as random and that of year and season of calving as fixed. The first lactation traits studied were first lactation milk yield (FLY), first lactation length (FLL) first service period (FSP) and first calving interval (FCI). The overall least squares means FLY, FLL, FSP and FCI were averaged as 2392.92±70.45 kg,317.70±15.87days, 160.20± 18.08 days and 448.90± 15.13 days, respectively. The effect of period of calving was not significant for all the first lactation traits under study except for FSP. Similarly, the effect of season of calving was not significant for all the first lactation traits except for FSP. The heritability estimates for different first lactation traits were obtained as 0.27±0.34, 0.14±0.39, 0.13±0.38and 0.21±0.26forFLY, FLL, FSP and FCI, respectively. The genetic correlation among first lactation traits were positive and varied from 0.16 to 0.59 except the genetic correlation of FLL with FSP and FCI which was low and negative. The phenotypic correlation among first lactation traits were low to high positive and varied from 0.11 to 0.76, respectively.

The objective of this work was to identify QTLs for liveweight in a candidate region of bovine chromosome 5. Half-sib families from two lines, one traditional and the other new, of Canchim beef cattle (5/8 Charolais + 3/8 Zebu) were genotyped for four microsatellite markers, including the microsatellite in the IGF-1 (insulin-like growth factor-1) promoter region. Significant differences in allele distribution between the two lines were found for three markers. Interval mapping analyses in this region indicated the presence of a QTL controlling birth weight (p < 0.05) and of a QTL influencing breeding value for yearling weight (p < 0.01) in the newer line of the breed. The previously identified interaction between the IGF-1 genotype and genetic group strengthens the hypothesis of a linked QTL rather than an IGF-1 effect on growth traits in the Canchim cattle.

Aberdeen Angus beef cattle from the Brazilian herd were studied genetically using restriction fragment length polymorphism (RFLP) of the κ-casein -HinfI (CSN3 -HinfI), β-lactoglobulin -HaeIII (LGB -HaeIII) and growth hormone AluI (GH-AluI) genes, as well as four microsatellites (TEXAN15, CSFM50, BM1224 and BM7160). The RFLP genotypes were determined using the polymerase chain reaction (PCR) followed by digestion with restriction endonucleases and electrophoresis in agarose gels. With the exception of the microsatellite BM7160, which was analyzed in an automatic sequencer, the PCR products were genotyped by silver staining. The allele and genotype frequencies, heterozygosities and gene diversity were estimated. The values for these parameters of variability were comparable to other cattle breeds. The genetic relationship of the Aberdeen Angus to other breeds (Caracu, Canchim, Charolais, Guzerath, Gyr, Nelore, Santa Gertrudis and Simmental) was investigated using Nei's genetic distance. Cluster analysis placed the Aberdeen Angus in an isolated group in the Bos taurus breeds branch. This fact is in agreement with the geographic origin of this breed.