https://hal.archives-ouvertes.fr/hal-01173575/document

Invited review: Body condition score and its association with dairy cow productivity, health, and welfare

Records on 1,180 young Angus bulls and heifers involved in performance tests were used to estimate genetic and phenotypic parameters for feed intake, feed efficiency, and other postweaning traits. The mean age was 268 d at the start of the performance test, which comprised 21-d adjustment and 70-d test periods. Traits studied included 200-d weight, 400-d weight, scrotal circumference, ultrasonic measurements of rib and rump fat depths and longissimus muscle area, ADG, metabolic weight, daily feed intake, feed conversion ratio, and residual feed intake. For all traits except the last five, additional data from the Angus Society ofAustralia pedigree and performance database were included, which increased the number of animals to 27,229. Genetic (co)variances were estimated by REML using animal models. Direct heritability estimates for 200-d weight, 400-d weight, rib fat depth, ADG, feed conversion,and residual feed intake were 0.17 +/- 0.03, 0.27 +/- 0.03, 0.35 +/- 0.04, 0.28 +/- 0.04, 0.29 +/- 0.04, and 0.39 +/- 0.03, respectively. Feed conversion ratio was genetically (r(g) = 0.66 ) and phenotypically (r(p) = 0.53) correlated with residual feed intake. Feed conversion ratio was correlated (r(g) = -0.62, r(p) = -0.74) with ADG, whereas residual feed intake was not (rg = -0.04, r(p) = -0.06). Genetically, both residual feed intake and feed conversion ratio were negatively correlated with direct effects of 200-d weight (r(g) = -0.45 and -0.21) and 400-d weight (r(g) = -0.26 and -0.09). The correlations between the remaining traits and the feed efficiency traits were near zero, except between feed intake and feed conversion ratio (r(g) = 0.31, r(p) = 0.23), feed intake and residual feed intake (r(g) = 0.69, r(p) = 0.72), and rib fat depth and residual feed intake (r(g) = 0.17, r(p) = 0.14). These results indicate that genetic improvement in feed efficiency can be achieved through selection and, in general, correlated responses in growth and the other postweaning traits will be minimal.

Genetic and phenotypic variance and covariance components for feed intake, feed efficiency, and other postweaning traits in Angus cattle

Fertility in the high-producing dairy cow ☆

Residual feed intake is defined as the difference between actual feed intake and that predicted on the basis of requirements for production and maintenance of body weight. Formulas were developed to obtain genetic parameters of residual feed intake from knowledge of the genetic and phenotypic parameters of the component traits. Genetic parameters of residual feed intake were determined for a range of heritabilities (h2 = .1, .3, or .5) for component traits of feed intake and production, and genetic (rg = .1, .5, or .9) and environmental (re = .1, .5, or .9) correlations between them. Resulting heritability of residual feed intake ranged from .03 to .84 and the genetic correlation between residual feed intake and production ranged from -.90 to .87. Heritability of residual feed intake depends considerably on the environmental correlation between feed intake and production. Residual feed intake based on phenotypic regression of feed intake on production usually contains a genetic component due to production. Residual feed intake based on genotypic regression of feed intake on production is genetically independent of production and its use is equivalent to use of a selection index restricted to hold production constant. Multiple-trait selection on residual feed intake, based on either phenotypic or genetic regressions, and production is equivalent to multiple-trait selection on feed intake and production. Residual energy intake in dairy cattle was examined as an example. Heritability of residual energy intake based on genotypic regression was close to zero and indicated that measurement of feed intake provides little additional genetic information over and above that provided by milk production and body weight. The principles outlined in this study have broader application than just to residual feed intake and apply to any trait that is defined as a linear function of other traits.

Genetic and statistical properties of residual feed intake

The Relationship Between Body Condition Score and Reproductive Performance

Genetic aspects of feed intake and efficiency in lactating dairy heifers

Genetic relationships between feed intake, efficiency and production traits in growing bulls, growing heifers and lactating heifers.

Genetic parameters for feed intake and feed efficiency in growing dairy heifers

A function to describe live-weight changes of dairy cows between two calvings is constructed. The following measurements were used: live-weight level (scale), pregnancy parameter, maximum decrease of live weight during the lactation and the time during lactation at which minimum live weight occurred.An analysis was carried out for each of 71 dairy cows of two genotypes, Dutch Friesian and Holstein Friesian crossbreds, given a high or a low concentrate diet. Data set 1 contained data of 40 weeks lactation and data set 2 data from calving to calving.The mean residual standard deviation per genotype-diet group ranged from 11 to 14 kg. The mean R2 ranged over the subgroups in data set 1 from 0·715 to 0·792 and in data set 2 from 0·857 to 0·906. Diet had a significant influence on the magnitude of the decrease in live weight during the lactation (71 v. 46 kg) and the mean time during the lactation at which minimum live weight occurred. The latter time ranged from day 58 to 100 over the four groups and a diet effect existed. The pregnancy parameter could not be estimated accurately based on measurements during the first 40 weeks of lactation. The correlation coefficient between the pregnancy parameter in data sets 1 and 2 ranged from +0·13 to +0·78. The other parameters showed coefficients from +0·82 to +0·99.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/321C4C935DA5D3CE88E9DB12F94544A1/S0003356100025332a.pdf/div-class-title-a-function-for-live-weight-change-between-two-calvings-in-dairy-cattle-div.pdf

S. Korver

Papers

Genetic aspects of feed intake and efficiency in lactating dairy heifers

Genetic relationships between feed intake, efficiency and production traits in growing bulls, growing heifers and lactating heifers.

Genetic parameters for feed intake and feed efficiency in growing dairy heifers

A function for live-weight change between two calvings in dairy cattle

Parameter Estimation of Milk Yield and Composition for 305 Days and Peak Production