Reducing stress is key to AI success
To use AI more successfully producers must breed, feed and house their cattle ‘appropriately’ to avoid clinical stress. That was the conclusion of a study, carried out by a team of scientists led by Hilary Dobson at the University of Liverpool, examining why is it getting more difficult to successfully AI cows
“Animal husbandry has failed to keep pace with improved genetics for yield,” Professor Dobson told delegates at the British Society of Animal Science’s international conference entitled: Fertility in dairy cows – bridging the gaps.
As milk yields have risen, first insemination pregnancy rates have fallen. The percentage of cows standing to be mated has also fallen – from around 90% in 1960 to around 55% in 2007 – as yields have risen and oestrus duration is also shorter in cattle today.
“Add to this the decline in labour on dairy units and it’s not surprising that fewer cows are being inseminated at the right time and with a declining degree of success.”
Milk progesterone profile studies also revealed more ‘atypical’ profiles and there are several cow health and management factors that are disrupting fertility and increasing the period of time between calving and pregnancy. Caesareans, for example, increase this interval to around 140 days, lameness to around 120 days and endometritis to around 115 days, compared to the desired interval of around 85 days.
“Stress caused by other production diseases, such as mastitis, also have a detrimental effect on fertility and the success of AI. Stress disrupts reproductive hormones,” said Professor Dobson.
“Preventative husbandry can go someway to making it easier to successfully inseminate cows. But breeding also has a role to play. Emphasis is still very much on production in most countries, and away from durability, and health and reproduction.
“More emphasis on the latter in cattle breeding indices, similar to the Danish selection index, is the way forward to help avoid clinical stress and improve fertility and AI success.”
Why is it getting more difficult to successfully AI dairy cows?
H Dobson, S L Walker, M J Morris, J E Routly and R F Smith
Dept Veterinary Clinical Science, University of Liverpool, Leahurst, Neston, Wirral, CH64 7TE, UK
Email: h.dobson@liverpool.ac.uk
