Critical factors to consider as farms arrive into breeding season
There are many factors involved in a satisfactory breeding season
*Check records of pre-service heats regularly and give attention to animals within 18 to 21 days of previous heat or service. The strategic use of tail-paint colours, or other aids, will simplify heat-detection. Good observation of cows early in the morning, at midday, and at late evening is essential.
*Stock bulls can become intermittently infertile during the breeding season, especially if they get lame or suffer any illness. So check bull fertility at the beginning of the season, but keep a close eye on him during the season. Check if cows are repeating.
*Vasectomised bulls with chin balls are being increasingly used for heat-detection, especially in large herds. At least two of these are necessary per 100 cows. Make sure chin balls are full of paint.
Vasectomised bulls are more active and are safer in the first year. All bulls should be tested free of BVD, and other contagious diseases. There are other aids to heat-detection on the market, including some computerised systems, which are giving fairly good results.
*Difficult calving, and twins, can reduce fertility by up to 50%, if proper veterinary follow-up treatment is not practiced.
Lame and sick cows will not only fail to show heat, but often they will not cycle. 93% of cows, which are properly fed and free of problems, should be showing heat within 40 days of calving.
nProper nutrition is important for a good breeding performance. Plenty of good grass should be the basis of this nutrition, plus supplementary feeding, as necessary. Remember, one of the main findings of the major Moorepark farm fertility trial is that cows that lose less than a quarter of a condition-score between calving and breeding are 50% more likely to be in-calf after six weeks of breeding than cows that lost over half a condition score. Therefore, do everything possible to avoid loss of condition in the run-up to, and during, the breeding season.
nData from some group analyses shows that cows with a high-fertility index had a calving interval of 374 days, and 84% of them reached their fourth lactation; cows with a low-fertility index had a calving interval of 407 days, and only 62% reached their fourth lactation.
How Many AI Straws?
Dairy farmers wishing to stay in business, or expanding, must realise that it takes five or six dairy AI straws to produce a two-year-old heifer calving-down. They should select the most suitable group of bulls for their herds, and get the best advice in doing so. Most farmers will be using some genomic-selected bulls, and because their reliability is relatively low, they should use a larger-than-usual team of sires. They should not use more than 50% genomic sires. Teagasc and ICBF are carrying out a large-scale project with sexed semen. If sexed semen can be proved to be successful, it will give groundbreaking advantages to dairy and beef industries.
AI v Bull
The main reason given for not having higher dairy AI usage in Ireland is the widely held opinion that fertility is better from a stock bull, especially with a once-per-day AI service.
But cattle-breeding experts have assured me that once-a-day AI service, at around the same time every day, can be as good as twice-a-day AI service or as a stock bull. However, due to the pressure of spring AI, the same-time-everyday service can be a problem in some areas. Convenience is another factor, as is the expectation of a higher proportion of heifer calves from a stock dairy bull. Some farmers express doubts about the semen quality from some AI bulls. But ICBF data proves that the proportion of heifers and bulls is similar with AI and stock bulls. Convenience is a legitimate concern, in some cases, but the danger aspect of bulls cannot be ignored. Also, some farmers do not appreciate that, on average, the progeny of AI bulls have the potential to be well over €100-per-lactation more profitable.
Milk Recording
To make maximum genetic progress, farmers would need to be milk-recording and have herd EBI values, and a lot of other information about their cows. Ideally, of course, replacements should be bred from the highest EBI cows and heifers. However, most farmers will need to breed them from most of their earliest-calving cows to get sufficient replacements.
Herd owners who supply the necessary information for their cows can get a password for their own herds into the ICBF website, where they get individual cow EBI, as well as individual-breeding advice. All of the advances in breeding technology start with milk-recording, and farmers who are not milk-recording will be left behind. Of course, milk-recording is also necessary for carrying out a proper mastitis-control programme.
