A New Perspective on Management of Reproduction in Dairy Cows: the Need for Detailed Metabolic Information, an Improved Selection Index and Extended Lactation

SUMMARYThe objective of the current study was to estimate heritability and genetic correlations between cystic ovarian disease (COD), foot and leg diseases (FLD) and displaced abomasum (DA) within the first three lactations of Holstein dairy cows. The 57 301 lactation records of dairy cows on 20 large dairy herds in Iran between January 2005 and June 2009 were analysed with three-trait threshold animal models, using Gibbs sampling methodology. The final model included the fixed class effects of herd-year, season of calving, the linear covariate effect of age at calving and additive direct genetic effect of animal. Posterior means of heritability in first, second and third lactations were 0·15, 0·18 and 0·22, respectively, for FLD; 0·09, 0·11, and 0·13 for COD; 0·05, 0·06, and 0·08 for DA. Posterior means of genetic correlations between diseases were low (from 0·03 to 0·14), within lactations; the largest estimates were for FLD and DA, and the lowest involved FLD and COD. Positive genetic correlations between diseases suggest that some general disease resistance factor with a genetic component exists. The results of the present study indicated the importance of health traits for considering in the selection index of Iranian Holstein dairy cows.

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A selection index for dairy cows

Animal Science ◽

10.1017/s0003356100001914 ◽

1983 ◽

Vol 37 (3) ◽

pp. 313-319 ◽

Cited By ~ 13

Author(s):

W. G. Hill ◽

G. J. T. Swanson

Keyword(s):

Dairy Cows ◽

Selection Index ◽

Best Linear Unbiased Prediction ◽

Linear Unbiased Prediction ◽

Genetic Base ◽

Sire Evaluation ◽

Selection Indices ◽

Best Linear Unbiased ◽

The Uk ◽

Method Of Evaluation

ABSTRACTThe rationale for a method of computing selection indices for dairy cows is outlined. It uses predicted transmitting abilities of sires from a best linear unbiased prediction or similar method of evaluation together with mean transmitting abilities (cow indices) of dams to estimate herd genetic levels. Indices for individual cows are computed using deviations from those of contemporaries in the herd of her sire's transmitting ability, her dam's index and her own production in each lactation.The method is being used in the UK, cow indices being expressed as transmitting abilities relative to the same fixed genetic base as for sire evaluation.

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Partitioning of dietary nitrogen in response to feeding cereal grain supplements to dairy cows during four periods of an extended lactation

Animal Production Science ◽

10.1071/an16479 ◽

2017 ◽

Vol 57 (7) ◽

pp. 1520

Author(s):

P. J. Moate ◽

S. R. O. Williams ◽

M. C. Hannah ◽

L. C. Marett ◽

M. J. Auldist ◽

...

Keyword(s):

Dairy Cows ◽

Total Nitrogen ◽

Control Group ◽

First Year ◽

Dietary Nitrogen ◽

Dietary Nutrients ◽

Cereal Grain ◽

Nitrogen Intake ◽

Ad Libitum ◽

Extended Lactation

Holstein–Friesian dairy cows managed in pasture-based systems are capable of lactating for considerably longer than the traditional 300 days. However, the partitioning of dietary nutrients in the second 300 days of an extended lactation has been shown to be different from that in the first 300 days. The partitioning of dietary nitrogen (N) was investigated using two groups of eight Holstein cows in four experimental periods of 6 days, at 110, 270, 450 and 560 days in milk (DIM). During each period, cows were housed in individual stalls where N intake and output were measured. Cows in a control group received a forage-based diet ad libitum, whereas cows in a second group received 5 kg DM of cereal grain and the basal forage diet ad libitum. N intake was positively related to outputs of milk N, urinary N and faecal N, and negatively to N-use efficiency (NUE). DIM was positively related to output of urinary N and negatively related to NUE and outputs of milk N and faecal N. The partitioning of N in the second year of an extended lactation was different from that in the first year, meaning that the partitioning of N reported for cows up to 300 DIM cannot be used to accurately predict the partitioning of N in cows beyond 300 DIM. Adding grain to the diet increased total nitrogen intake but decreased NUE. However, it is plausible for the addition of cereal grain to the diet of dairy cows to increase NUE, but only when the concentration of dietary crude protein decreases and any increase in dry-matter intake is small, such that total nitrogen intake is decreased.

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