Sep 5 2012
By Sarah Guy, medwireNews Reporter
The length of time a dairy cow has been lactating affects their feeding habits and their potential for lameness, show study results, with decreased dry matter intake displayed by cows in early lactation.
The findings have implications for the cows' welfare and productivity, says the team in Applied Animal Behaviour Science, since reduced feed intake due to lameness could exacerbate the severity and duration of the negative energy balance experienced by high-yielding dairy cows during early lactation.
"This in turn will predispose the animal to immunosupression, metabolic disorders, and reproductive failures," explain Maeve Palmer, from Queen's University in Belfast, UK, and co-investigators.
Lameness affects over a third of UK dairy herds and can result in infertility and an average 360 kg loss of milk production per lactation, which becomes an economic problem, they add.
At 60 and 120 days postpartum, representing early and mid-lactation, the researchers assessed feeding behaviors including number and duration of meals eaten, in 45 animals. They assigned locomotion scores to each cow as an indicator of lameness, where a score above 3.0 indicates clinical lameness, and a score over 3.5 denotes severe lameness.
A total of 40% and 51% of animals were clinically lame at 60 and 120 days, respectively. At both time points, animals with higher locomotion scores ate significantly fewer meals over 24 hours with approximately 6 meals eaten by cows with scores of 3.5 and 10 meals eaten by cows with a score of 2.0, at 60 days postpartum.
Higher locomotion scores were also significantly associated with shorter durations of feeding at both time points, at approximately 100 minutes among cows with a score of 4.5 compared with 220 minutes in cows with a score of 2.0.
Conversely, while total intake of dry matter from the basal ration was significantly negatively associated with locomotion score at 60 days postpartum, this association was lost at day 120.
"The lower [dry matter intake] observed in lame animals during early lactation could interact with metabolic factors to exacerbate the consequences of lameness," suggest Palmer and colleagues.
The observation "may be linked to changes in hormonal profiles and the ability of animals in early lactation to break down body tissues," they add.
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