Genetic parameters across lactation for feed intake, fat- and protein-corrected milk, and liveweight in first-parity Holstein cattle

Abstract

Breeding values for dry matter intake (DMI) are important to optimize dairy cattle breeding goals for feed efficiency. However, generally, only small data sets are available for feed intake, due to the cost and difficulty of measuring DMI, which makes understanding the genetic associations between traits across lactation difficult, let alone the possibility for selection of breeding animals. However, estimating national breeding values through cheaper and more easily measured correlated traits, such as milk yield and liveweight (LW), could be a first step to predict DMI. Combining DMI data across historical nutritional experiments might help to expand the data sets. Therefore, the objective was to estimate genetic parameters for DMI, fat- and protein-corrected milk (FPCM) yield, and LW across the entire first lactation using a relatively large data set combining experimental data across the Netherlands. A total of 30,483 weekly records for DMI, 49,977 for FPCM yield, and 31,956 for LW were available from 2,283 Dutch Holstein-Friesian first-parity cows between 1990 and 2011. Heritabilities, covariance components, and genetic correlations were estimated using a multivariate random regression model. The model included an effect for year-season of calving, and polynomials for age of cow at calving and days in milk (DIM). The random effects were experimental treatment, year-month of measurement, and the additive genetic, permanent environmental, and residual term. Additive genetic and permanent environmental effects were modeled using a third-order orthogonal polynomial. Estimated heritabilities ranged from 0.21 to 0.40 for DMI, from 0.20 to 0.43 for FPCM yield, and from 0.25 to 0.48 for LW across DIM. Genetic correlations between DMI at different DIM were relatively low during early and late lactation, compared with mid lactation. The genetic correlations between DMI and FPCM yield varied across DIM. This correlation was negative (up to -0.5) between FPCM yield in early lactation and DMI across the entire lactation, but highly positive (above 0.8) when both traits were in mid lactation. The correlation between DMI and LW was 0.6 during early lactation, but decreased to 0.4 during mid lactation. The highest correlations between FPCM yield and LW (0.3-0.5) were estimated during mid lactation. However, the genetic correlations between DMI and either FPCM yield or LW were not symmetric across DIM, and differed depending on which trait was measured first. The results of our study are useful to understand the genetic relationship of DMI, FPCM yield, and LW on specific days across lactation.

Hot topic: Definition and implementation of a breeding value for feed efficiency in dairy cows

“…Although calculating RFI for only 305 d of the year was conservative, we assumed that RFI is the same trait across lactations, which may not be the case. For example, the correlation between DMI in early and late lactation is relatively weak (Manzanilla Pech et al, 2014). As feed intake measurements were made on calves at about 6 mo of age, this is also likely to reflect a conservative approach.…”

Genetic parameters between feed-intake-related traits and conformation in 2 separate dairy populations—the Netherlands and United States

“…Another option is to use other traits as predictors, such as production traits (e.g., milk, fat, and protein content) that have been shown to have strong genetic correlations with DMI Veerkamp and Brotherstone, 1997;Manzanilla-Pech et al, 2014). Other possible predictor traits are conformation traits or linear type traits, which describe a range of visual characteristics of an animal (Berry et al, 2004), or BCS, which is an estimate of the fat storage (Waltner et al, 1993).…”

Genetic and phenotypic associations of type traits and body condition score with dry matter intake, milk yield, and number of breedings in first lactation Canadian Holstein cows

“…They found an overall heritability estimate of feed intake of 0.34 when experimental data were collated from nine countries. Heritability estimates for DMI across lactation ranged from 0.21 to 0.40 in a recent study on the firstparity Holstein cows by Manzanilla-Pech et al (2014). Manafiazar et al (2016) obtained higher heritability estimate for lactation total DMI (0.27) in Canadian cows indicating that regulation of feed intake has a substantial genetic contribution and can be successfully altered through selection (Shonka et al 2015).…”