Good herd reproductive performance is a key driver of profit on pasture-based dairy farms, and Poowong, Vic, farmer Brian Corr has reaped the rewards of focusing on improvement in herd fertility in the past few seasons.
Mr Corr runs what would be considered a low-input system of milk production, with minimal use of supplementary concentrate (he is on target to feed 300 kilograms grain/cow to the herd across the current lactation, with the herd 100 per cent spring calving).
It is worth noting that this has not had any negative effect on reproductive performance, with recent pregnancy testing indicating a six week in-calf rate of 69pc, a herd empty rate of just 5.9pc and a six-week calving rate last spring of greater than 80pc.
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The farm has demonstrated a dramatic improvement in reproductive performance compared with three years ago when Mr Corr first arrived and the herd empty rate was about 30pc.
So how has such a dramatic improvement been made in the last few seasons?
"We decided to switch to a spring-calving only system to better match pasture growth rates to peak herd feed demand," he said. "In addition, calving start date is now July 18, a few weeks earlier than it used to be. While this can leave us with a feed deficit very early in the lactation, it has benefits from late August onwards when the majority of cows are calved and pasture growth rates in the area tend to rapidly increase".
The average calving date on the farm last year was August 1 (heifers calved from July 11). The joining period lasted 14 weeks this year, but the aim is to get it down to 10 weeks from next season. Another benefit of the earlier calving date was the fact that joining now starts in mid-October, leaving them less likely to experience extreme heatwaves during the breeding season.
Mr Corr has previously found significantly poorer conception rates when cows have been served in November during spells of very hot days, something which has also been anecdotally reported on other farms in Gippsland.
The farm used to be twice-a-day milking, with all cows milked once-a-day for the first three weeks of lactation. This season, they decided to stick with OAD milking throughout the entire lactation. The decision has been something with which they are happy.
"We have lower yield per cow this year, which will probably be in the order of 50-60 kilograms milk solids/cow across the lactation. However, last year we fed approximately 900kg grain/cow and this year we will only fed 300, so the lower yield per cow this season is not just associated with the switch to OAD. We feel that the OAD milking has helped maintain body condition scores in the period around mating and helped conception rates."
The key aim is to have as many cows as possible calving early in the calving period. This maximises the days in milk of each cow in the seasonal calving system before dry off, while also giving cows enough time post-calving to cycle again before the mating start date of October 15.
The aim is to have 90pc of the cows calve within six weeks of the calving start date of July 18, and they are almost there with over 80pc achieving this target last spring. Heifers start being mated one week before the main herd.
Mr Corr's organisation and adherence to a strict plan around mating has also been a factor in the fertility of the herd. Pre-breeding heat detection starts five weeks prior to main herd mating start date. Cows not cycling within two weeks of mating start date are metri-checked for endometriosis and any dirty cows treated with Metricure.
Synchronisation tools such as prostaglandin and Controlled Internal Drug Releases (CIDRs) are used to bring as many cows as possible forward to the start of the mating period.
This method resulted in a 95pc herd submission rate for AI in the first two weeks of joining last spring. When initially dealing with a spread out range of calving dates in the herd in the past couple of years, Mr Corr used a limited amount of induction to bring cows calving dates forward to the start of the calving period and culled/sold any cows, which were well outside the desired calving period in spring, replacing them with crossbred heifers on the point of calving in July/August. "It's crucial to do whatever you can to tighten up the calving pattern first, before focusing on other aspects of breeding and repro, if you want to solve a fertility problem on the farm quickly," he said.
What is the farms approach to genetics and bull selection? "We import Holstein Friesian semen from Ireland and Jersey from New Zealand to use on heifers and cows submitted early in the joining period," he said. "Replacements are bred with a focus on daughter fertility, increased milk solids and low maintenance. We also only use A2 bulls with an eye on potentially transition the herd in that direction in the future".
Article courtesy of How Now Gippy Cow
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