Genetic parameters for longitudinal behavior and health indicator traits generated in automatic milking systems
Genetic (co)variance components were estimated for alternative functional traits generated by automatic milking systems (AMSs), and reflecting dairy cow behavior and health. Data recording spanned a period of 30 days and included 70 700 observations (visits to the AMS) from 922 Holstein cows kept...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-04-01
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| Series: | Archives Animal Breeding |
| Online Access: | https://www.arch-anim-breed.net/61/161/2018/aab-61-161-2018.pdf |
| Summary: | Genetic (co)variance components were estimated for alternative functional
traits generated by automatic milking systems (AMSs), and reflecting dairy cow
behavior and health. Data recording spanned a period of 30 days and included
70 700 observations (visits to the AMS) from 922 Holstein cows kept in three
German farms. The three selected farms used the same type of AMS and specific
selection gates allowing <q>natural cow behavior on a voluntary basis</q>. AMS
traits used as behavior indicator traits were AMS visits per cow and day as
binary traits, with a threshold for equal to or greater than three visits (VIS3)
and equal to or greater than four visits (VIS4), knocking off the milking device
with a threshold of at least one udder quarter, also as a binary trait (KO),
milking duration of each AMS visit in minutes (DUR), average milk flow in
kg min<sup>−1</sup> (AMF), and the interval between two consecutive milkings (INT).
Electrical conductivity (EC) of milk from each udder quarter and in total was
used as a health indicator trait. For genetic analyses, in univariate and
bivariate models, linear and generalized linear mixed models (GLMMs) with a
logit link function were applied to Gaussian distributed and binary traits,
respectively. The heritability was 0.08 ± 0.03 for VIS3,
0.05 ± 0.05 for VIS4, 0.03 ± 0.03 for KO, 0.19 ± 0.07 for
DUR, 0.25 ± 0.07 for AMF, and 0.07 ± 0.03 for INT. Heritabilities
for EC varied between 0.37 ± 0.08 and 0.46 ± 0.09, depending on
the udder quarter. On the genetic scale, an increased number of AMS visits
(VIS3 and VIS4) were associated with an increase of KO (<i>r</i><sub>g</sub> = 0.24 and
<i>r</i><sub>g</sub> = 0.55, respectively). From a genetic perspective, high-milk-yielding
cows visited the AMS more often (<i>r</i><sub>g</sub> = 0.49 for VIS3 and <i>r</i><sub>g</sub> = 0.80 for VIS4), had a faster AMF (<i>r</i><sub>g</sub> = 0.40), and shorter INT
(<i>r</i><sub>g</sub> = −0.51). When considering these traits as behavior indicator
traits, selection of cows with desired temperament simultaneously increases
milk yield. An increase of automatically and objectively recorded AMS traits
with moderate heritabilities justifies modifications of dairy cattle breeding
goals towards higher emphasis on behavioral traits, especially when
developing specific robot indices. Nevertheless, ongoing research in this
regard with a larger data is suggested in order to validate the results from
the present pilot study. |
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| ISSN: | 0003-9438 2363-9822 |