As breeding season approaches, it is highly worthwhile taking a look at how you can improve fertility in your herd. Not only will this be of benefit to your herd but will also provide long term increase profits.
At Elite Bovine Genetics we believe bull selection, husbandry and the correct fertility management increase the positive results of compact calving and fewer empty cows. Starting at the time of drying off, cows should have had a condition score of 2.75 and a condition score of 3 to 3.25 at calving. When calving, cows which where breed to hard calving bulls should be given more attention. Calving difficulty, besides its effect on calf and cow mortality and on milk yield, also decreases cow fertility and performance. Data clearly shows that when calving difficulty increases, conception rates drop on the first and subsequent inseminations. This reduction in conception rate is due to abnormalities arising from the calving difficulty including increased uterine infection and delayed uterine involution. Difficult calving pushes out the interval to the cow’s first heat, for optimal reproductive performance, calving difficulty must be minimised. Two factors that greatly influence calving difficulty are cow age and sire breed. The incidence of calving difficulty is four to eight times higher in first calving heifers than in mature cows and about twice as high in second calvers as in mature cows. Breed of sire and indeed the individual sire within a breed, should be carefully selected for use on heifers and on young cows to minimise the risk of calving difficulty and infertility. While it is an increasing practice to breed late calving dairy cows to continental sires, the combined effects of the longer gestation and the increased incidence of calving difficulty make it even more difficult to achieve a 365-day calving interval in such cows.
Post calving the cow needs to maintain a positive energy balance to increase the chance of conception and maintaining a viable embryo. Once the cow has calved down the following practice is necessary to understand the cow’s oestrous cycle. Record all of your cow’s heat patterns; this will help to identify your problematic cows. From now until breeding season you will have built up an excellent database of information while also picking up cows that have luteal or follicular cysts and cows that have become inactive post calving. Furthermore, watching for a dirty discharge from your cows when they are lying down will give you a very good indication if there is infection in the uterus.
At this stage I would highly recommend scanning your herd. Scanning will detect and confirm those problematic cows. Each cow that present a problem can be treated accordingly. One excellent example of husbandry on a farm which I regularly scan in was a herd of 250 cows and 70 heifers in Tipperary. It is a spring calving herd that artificial inseminates once a day. All cows are examined with the scanner per breeding season, bulls are selected to suit the cows, and all cows are artificially inseminated for 7 weeks and moped up after with a Friesian bull. When the breeding season was over and I went back to scan again in September, there was three cows and two heifers not in calve out of 320 animals, with 85% of the herd scanned in-calf to the AI period. Excellent herd management and bull selection had a massive roll to play in achieving such a positive result.
The advantages of using Artificial Insemination are clearly to be seen, wide gene pool to choose from, insemination dates for calving and elimination of dangerous or unfertile bulls.
There are some disadvantages which can be overcome through proper management. Artificial Insemination requires more labour, facilities and managerial skills than natural service but these aren’t a problem on most modern farms today.
Timing of insemination is very important. Cows which are in heat should be left for twelve hours before inseminating, but often this isn’t practical as cows entering oestrus might not suit your timetable twelve hours later. The best practice when you’re artificial inseminating your cows is the am/pm rule. If the cow is in oestrous in the morning AI her in the evening, if she is in oestrous in the evening, AI her in the morning.
Another method adopted by bigger dairy herds is once a day AI. This method works well in larger herds with an acceptable amount of losses due to untimely AI.
When depending on a bull for your reproductive programme it is not a case of opening the gate and letting the bull out to the field. Bull reproductive performance is influenced by several factors including: testicular development; semen quality; libido; mating ability; and physical soundness. Another factor worth remembering is the ratio of bulls to cows. Young bulls less than 18 months should not be grouped with anything more than 25 cows where bulls from 2-3 years can handle up to 35 cows. Older bulls have the maturity to handle more cows but if you have a big herd it is well worth rotating your bulls at every milking.
When you’re scanning your cow’s pre breeding season it is well worth evaluating your bull’s fertility. A fertility and semen evaluation on three bulls would cost no more than €150 euro where infertile bulls could cost you thousands in empty cows. An examination combined with a semen evaluation one month before the start of the breeding season will help to identify the infertile bulls; however it will not identify sub-fertile bulls. Furthermore, it should be realised that a bull may not remain fertile for all of his working life or indeed throughout a single mating season. For example, a bull that is ill with a raised temperature for a number of days may have a period of temporary infertility about 40 to 60 days later.
Similarly, injury to the penis, sheath or prepuce, while not necessarily affecting mounting behaviour, can prevent mating. Therefore, the bull should be observed regularly for serving ability and all mating dates recorded. Such recording will help identify infertile or sub-fertile bulls at an early stage.
For improved husbandry and fertility management of your herd, make time to evaluate your herd status. Ask yourself what I can do pre breeding season to improve conception and the viability of the embryo. Make time to scan your herd, picking out your problematic cows and sort any problems prior to the breeding season. If you are relying on stock bulls, take the time to fertility test the bulls now. Infertility with your stock bull should be sorted now rather than noticing a problem half way through the breeding season. If you are using AI, make time to pick the bull that suits your cows. The decisions you make now affect your breeding, fertility and cow health into the further. Lastly, I would like to take this opportunity to wish everyone well for the upcoming season and if you would like to maximise your herd’s potential the team here at Elite Bovine Genetics are more than happy to help.