Bayesian inference of genetic parameters for test-day milk yield, milk quality traits, and somatic cell score in Burlina cows

Abstract

The aim of the study was to infer (co)variance components for daily milk yield, fat and protein contents, and somatic cell score (SCS) in Burlina cattle (a local breed in northeast Italy). Data consisted of 13,576 monthly test-day records of 666 cows (parities 1 to 8) collected in 10 herds between 1999 and 2009. Repeatability animal models were implemented using Bayesian methods. Flat priors were assumed for systematic effects of herd test date, days in milk, and parity, as well as for permanent environmental, genetic, and residual effects. On average, Burlina cows produced 17.0 kg of milk per day, with 3.66 and 3.33 percent of fat and protein, respectively, and 358,000 cells per mL of milk. Marginal posterior medians (highest posterior density of 95%) of heritability were 0.18 (0.09-0.28), 0.28 (0.21-0.36), 0.35 (0.25-0.49), and 0.05 (0.01-0.11) for milk yield, fat content, protein content, and SCS, respectively. Marginal posterior medians of genetic correlations between the traits were low and a 95 percent Bayesian confidence region included zero, with the exception of the genetic correlation between fat and protein contents. Despite the low number of animals in the population, results suggest that genetic variance for production and quality traits exists in Burlina cattle.

Estimation of genetic and phenotypic parameters for bacteriological status of the udder, somatic cell score, and milk yield in dairy sheep using a threshold animal model

“…However, the heritability estimate for SCS in this study falls within the range (0.04-0.16) reported in the literature for sheep (e.g., Barillet et al, 2001;Baro et al, 1994;Hamann et al, 2004). Using the same Bayesian approach, Penasa et al (2010) obtained a value of 0.05 for Table 1 Descriptive statistics for milk yield and somatic cell score both considering the whole sample and according to the health status (infected or not infected). the SCS heritability in a small autochthonous dairy cattle breed; whereas, other authors found higher values in German Holstein (Hinrichs et al, 2005) and Danish Holstein breed (Madsen and Odegard, 2006).…”

Temporal Variation in Genetic Diversity and Population Structure of Burlina Cattle Breed

“…These preliminary research was fundamental in describing genetic diversity estimates in BUR, but provided only limited and static information on how breed variability and distinctness were developing. Our results spanned a 20-year period including animals from 1991 to 2010 overlapping those recorded by pedigree information (Battagin et al, 2010) and previous molecular studies (Del Bo et al, 2001;Dalvit et al, 2008). The mean MNA value found in BUR (6.46) is comparable to that previously obtained by Dalvit et al (2008) for the same breed (6.70) and to that of IHF (6.35), and larger than the value reported by Del Bo et al (2001) (5.59).…”

“…However, we do not know if this decline occurred as a rapid series of bottlenecks and if the decline in genetic diversity is still ongoing in the breed- ing population. Battagin et al (2010) recently analysed pedigree information of BUR available since 1980. In the last ~30 years the number of recorded individuals increased significantly together with the number of inbred animals; at the beginning of the conservation programme, bulls of the local breed were mated to pure and crossbred Burlina cows and then backcross to Burlina was practiced (Bittante et al, 1992).…”

“…According to Battagin et al (2010) the FIS in BUR started to increase from 1992 and reached the 4.81% in 2009 but the absence of pedigree records, before 1980s, limits the analysis of inbreeding using only pedigree information. According to our results, using microsatellite markers, FIS was limited in the range of 0.006 (2006) to 0.108 (2005) without any temporal variation trend (Figure 1d).…”

“…A regional conservation programme was set up since 1980s aiming to contrast the reduction of population size and the increasing of inbreeding (Bittante et al, 1992). More recently, Pretto et al (2009) compared milk production parameters of BUR to that of Italian Holstein Friesian (IHF) breed; Penasa et al (2010) analysed genetic parameters of production and quality traits of BUR and Pacini et al (2008) studied the k-casein variants using polymerase chain reaction-temperature gradient gel electrophoresis (PCR-TTGE) for the same breed. The importance of BUR, from an economical point of view, is related to the production of a typical cheese called Morlacco and, from a rearing point of view, to its frugal characteristic that along with its longevity and better functional performances are of particular interest especially in marginal areas (Pretto et al, 2009).…”