Flighty cows are likely to respond to stress, e.g. change of environment, by producing less milk. This and other intriguing points have been noted during a study of dairy cow temperament at AgResearch.
That's the message DairyNZ developer Howard de Klerk delivered at a Southland, NZ Demonstration Farm recently.
The body condition score (BCS) of cows at calving and the amount of condition they lose between calving and mating impacts significantly on reproduction rates, he stresses. This in turn affects the calving duration, with late cycling cows often falling outside the target period and forcing inductions. This has been the key strategy for reducing inductions on the Southland Demonstration Farm.
De Klerk says cow condition must be actively managed to improve reproductive performance and reduce inductions, with the goal of calving cows at a BCS 5, limiting condition loss in early lactation to BCS 1 and having cows at a BCS 4 at the planned start of mating. He says New Zealand data shows cows calving at a BCS 4, instead of 5, are 7% less likely to be cycling at mating time.
Observations on the demonstration farm indicate that 34% of cows calving at BCS 5 were not observed cycling at the planned start of mating, compared with 54% at BCS 4. Milking frequency can be adjusted and silage fed in late autumn to achieve BCS5 by calving.
"Otherwise it just goes from bad to worse - if she's late this year, she'll start cycling later next season and it becomes a horrible cycle."
Research from Lincoln University's dairy farm supports this and shows that early calving cows and heifers have a greater chance of conceiving early and calving earlier next year. De Klerk also says cows that have not started cycling at the planned start of mating have a 16% lower six-week in calf rate and a 6% higher empty rate.
This was confirmed at the demonstration farm last season, when there was a 23% difference in six week in-calf rates, with cows cycling at mating having an early pregnancy rate of 78%, compared to 55% for non-cycling cows.
A more condensed calving pattern can also be achieved by selling cows due to calve after 12-weeks.
In Southland, this involves many of the older cows in the herd.
Those remaining cows that calve later than week nine will be induced, not exceeding the allowable 8% rate for this season, so by calving these cows early it increases their chances of conceiving early and calving early next season, he explains.
De Klerk points out that in future it will be necessary to reduce the mating period to between 10 and 12 weeks to eliminate inductions. Removing the bull from the herd earlier will also assist with this.
While synchronising heifers and mating them a week to ten days earlier than the main mob, to give them some extra time to start cycling by the planned start of mating, can also help condense subsequent calving patterns and reduce inductions.
"This effectively gives heifers 10-12 days longer to get back into shape and start cycling."
Maintaining the herd age structure also has implications, with cows around ten years-plus often slower to get into calf.
"Inductions have been a convenient tool, but it's been like the ambulance at the bottom of the cliff. By being more pro-active around managing BCS and mating management, we can reduce the need for inductions."