Selection for milk coagulation properties predicted by Fourier transform infrared spectroscopy in the Italian Holstein-Friesian breed

Abstract

Milk coagulation is based on a series of physicochemical changes at the casein micelle level, resulting in formation of a gel. Milk coagulation properties (MCP) are relevant for cheese quality and yield, important factors for the dairy industry. They are also evaluated in herd bulk milk to reward or penalize producers of Protected Designation of Origin cheeses. The economic importance of improving MCP justifies the need to account for this trait in the selection process. A pilot study was carried out to determine the feasibility of including MCP in the selection schemes of the Italian Holstein. The MCP were predicted in 1,055 individual milk samples collected in 16 herds (66 ± 24 cows per herd) located in Brescia province (northeastern Italy) by means of Fourier transform infrared (FTIR) spectroscopy. The coefficient of determination of prediction models indicated moderate predictions for milk rennet coagulation time (RCT=0.65) and curd firmness (a₃₀=0.68), and poor predictions for curd-firming time (k₂₀=0.49), whereas the range error ratio (8.9, 6.9, and 9.5 for RCT, k₂₀, and a₃₀, respectively) indicated good practical utility of the predictive models for all parameters. Milk proteins were genotyped and casein haplotypes (αS₁-, β-, αS₂-, and κ-casein) were reconstructed. Data from 51 half-sib families (19.9 ± 16.4 daughters per sire) were analyzed by an animal model to estimate (1) the genetic parameters of predicted RCT, k₂₀, and a₃₀; (2) the breeding values for these predicted clotting variables; and (3) the effect of milk protein genotypes and casein haplotypes on predicted MCP (pMCP). This is the first study to estimate both genetic parameters and breeding values of pMCP, together with the effects of milk protein genotypes and casein haplotypes, that also considered k₂₀, probably the most important parameter for the dairy industry (because it indicates the time for the beginning of curd-cutting). Heritability of predicted RCT (0.26) and k₂₀ (0.31) were close to the average heritability described in literature, whereas the heritability of a₃₀ was higher (0.52 vs. 0.27). The effects of milk proteins were statistically significant and similar to those obtained on measured MCP. In particular, haplotypes including uncommon variants showed positive (B-I-A-B) or negative (B-A(1)-A-E) effects. Based on these findings, FTIR spectroscopy-pMCP is proposed as a potential selection criterion for the Italian Holstein.

The effect of selection on casein genetic polymorphisms and haplotypes in Italian Holstein cattle

“…For CSN3, the A allele is still the most frequent in the Holstein, but the frequency of the B allele is constantly increasing (from 18.6% before 1990 to more than 30% nowadays), whereas in the Jersey B is the predominant variant (90%). Table 3 shows the results of the b-k casein haplotype frequencies obtained in rIH and IJ, compared with previously reported haplotypes frequencies in the Italian Holstein breed (Boettcher et al 2004;Chessa et al 2014). As it can be noted the predominant haplotype in the Holstein is the A 2 -A haplotype (about 48%), followed by the A 1 -A (22-28%), which clearly depends on the high frequency of the k-casein A variant.…”

A mycotoxin-deactivating feed additive counteracts the adverse effects of regular levels of Fusarium mycotoxins in dairy cows

“…Representative milk samples were taken at 0, 14, and 21 d during each experimental period at the morning milking using an automatic sampling unit. Butterfat, protein, lactose, casein content, titratable acidity, and coagulation properties [rennet clotting time (r), curd firming time (K20), and curd firmness at 30 min (a30)] were measured using infrared measurements (MilkoScan FT 120, Foss Electric, Hillerød, Denmark) according to Chessa et al (2014). The fat and protein content and the fatto-protein ratio were also calculated.…”

Monensin controlled-release capsule administered in late-pregnancy differentially affects rumination patterns, metabolic status, and cheese-making properties of the milk in primiparous and multiparous cows

“…Milk samples were collected from the morning milking at 7, 14, 21 and 28 DFC (Figure 1). The milk composition (fat, protein, lactose, casein contents, and titratable acidity) and cheese-making properties (rennet clotting time [r], curd-firming rate [k 20 ], and curd firmness at 30 minutes [a 30 ]) were measured by using infra-red instrumentation (MilkoScan FT 120, Foss Analytics, Hillerød, Denmark) as previously reported (Chessa et al 2014). Fat and protein outputs were also calculated.…”