Additive and dominance effects of the α_s1-casein locus on milk yield and composition traits in dairy goats

Abstract

The objective of this study was to evaluate the effects of the CSN1S1 locus polymorphism on 305-d records of milk, fat, protein, lactose and total solids yields, fat, protein, lactose and total solids contents in Mexican dairy goats. A total of 514 lactation records belonging to Alpine (n=60), Saanen (n=105) and Toggenburg (n=74) goats, born from 2003 to 2006 in three herds were used. Discrimination between alleles E, F, N, A* (CSN1S1 A, G, H, I, O1 and O2) and B* (CSN1S1 B1, B2, B3, B4, C and L) were made by amplification of fragments of the gene CSN1S1 and digestion with the restriction endonuclease XmnI. In order to estimate additive and dominance effects, data sets including (1) all genotypes, and (2) only homozygote genotypes, were analysed using linear mixed models. The allele A*, had significant additive effects for protein content (0·21±0·07%; P=0·002) and total solids content (0·66±0·23%; P=0·005) when compared with allele F. An unfavourable additive effect of allele A* on milk yield was found in the Alpine breed (-81·4±40·2; P=0·046) when compared with allele F. Favourable dominance effects were found for some genotypes (P<0·05) for milk yield (A*N and B*N), fat yield (A*N and B*E), protein yield (A*N and B*E), lactose yield (A*N) and total solids yield (A*N). Also, unfavourable dominance effects were found (P<0·05) for protein content (A*B* and A*N) and total solids content (A*B*, A*N, and A*F). Allele A* was the only one with a positive effect for protein content. Significant allele-year interaction effects were also observed. The presence of significant dominance effects, estimated between specific pairs of alleles, challenged the purely additive nature of the genetic effect at the CSN1S1 locus. Implications from use of CSN1S1 effects in goat breeding programmes are presented.

Determining the frequencies of B1, B2, B3 and E alleles of the <i>CSN1S1</i> gene and their effects on milk yield and composition in Saanen goats

“…The fat, protein and lactose percentages of milk in the Saanen goat breed with B3/B3 genotype were found to be lower than specified in Sarda goats by Balia et al (2013). Similar data were recorded for fat (3.4%) and lactose percentages (4.3%) of milk on Saanen, Alpinee and Toggenburg goats with BB by Flores et al (2012). Protein (2.9%) and TS percentages (10.7%) were found to be higher than the current data in Saanen with B3/B3.…”

“…Fat percentage was lower in Saanen goats with EE genotype (as shown in Table 3) than the Murciano-Granadina goat breed (Caravaca et al, 2009). The results of Flores et al (2012) showed that the fat and total solid percentages of milk in Saanen, Alpine and Toggenburg were 3.18% and 10.79%, respectively. Compared with the study of Flores et al (2012), fat and TS percentages were higher in Saanen goats with EE and NE/NE genotypes in the present study.…”

“…The results of Flores et al (2012) showed that the fat and total solid percentages of milk in Saanen, Alpine and Toggenburg were 3.18% and 10.79%, respectively. Compared with the study of Flores et al (2012), fat and TS percentages were higher in Saanen goats with EE and NE/NE genotypes in the present study. NE allele increased the fat and TS percentages of milk statistically in Saanen goats.…”

“…Dominant effects were found for some genotypes for milk yield (AN and BN), fat yield (AN and BE), protein yield (AN and BE), lactose yield (AN), and TS yield (AN). Unfavourable dominance effects were found for protein contents (AB and AN) and TS contents (AB, AN, and AF) in Alpine, Saanen and Toggenburg goats (Vázquez-Flores et al, 2012). Despite the number of studies that determined the frequency of CSN1S1 alleles, investigations into the effects of the CSN1S1 gene on milk yield and composition are limited.…”

Differential Expression of the Alpha S1 Casein and Beta-Lactoglobulin Genes in Different Physiological Stages of the Adani Goats Mammary Glands

“…The breeding values of the animals were estimated based on milk yield. Therefore, these differences are very important as they affect CSN1S1 and BLG genotypes on transcriptional level, milk yield, and proteins that have been reported (2,33-35). In addition, the differential expression between breeding value groups may be caused by genetic variation that is related to breeding value groups.…”