Getting the basics right for successful breeding
The breeding season is like the championship; you have to hit the ground running for the first round, as defeat here will result in cracks a few weeks later in the qualifiers and if we do not get it right here, we are facing relegation.
Pregnancy Rate = Submission Rate x Conception Rate
Put simply, the equation above is what fertility is all about. Empty cows or cows not scanned in calf is usually the measurement of a fertility issue. To solve such issues, we need to take a closer look at the numbers, to determine why this is happening. Sometimes, small changes can yield big benefits. If we are disappointed with 15 per cent of cows not in calf in a 100-cow herd, we can get that rate below 10 per cent.
Four key areas to focus on for the breeding season are:
Mating start date;
Body condition score;
Mineral management; and
Mating start date.
Traditionally, many herds will begin their breeding season during the last week of April. The decision of when breeding should start depends on when you want your cows to calve next spring. Your breeding start date should be based on matching feed supplies on your farm. If your farm has a late turnout date to grass in a spring-calving system, the breeding start date needs to match this.
Completing three weeks of pre-breeding checks, prior to breeding, is advisable as it gives a chance to pick out cows that may be non-cycling. Non-cycling cows often relates back to an issue at calving, such as milk fever, retained placenta, or metritis. Another issue which can be picked up at pre-breeding checks are silent heats–cows that show no signs of bulling at all. Generally speaking, if a cow does not show signs of bulling 42 days post calving, then this animal needs to be examined and treated by your vet.
Choose your breeding start date and end date effectively. Many herds. through the use of sexed semen, allow for more precise planning. Also, the traditional 12-week breeding has now been reduced to 10 weeks on certain farms using automatic heat detection.
Body condition score
Ideally, cows should have a minimum body condition score (BCS) of 2.75-3.0 at the start of breeding. Achieving a body condition score of 3.0 greatly helps increase conception rates of the herd. Cows that are milking off their back and have a poor BCS of less than 2.5 will struggle to go in calf, as they will not have enough energy to maintain a pregnancy. BCS needs to be monitored closely post calving as well, since cows that are not supplied with adequate amounts of energy will lose excess weight leading to a drop in BCS. Cows should be scored regularly in a crush throughout the year to monitor their BCS.
Trying to put condition on cows during the breeding season is ineffective, so it is best to start the breeding season on a rising plane of nutrition. Often, cows are out day and night on grass, with very little ration being fed. During breeding season, however, put the cows’ needs first and the grass second. Cows require that their full energy demands are by achieving good dry matter (DM) intakes. A lactating cow can eat 3.5 per cent of her bodyweight in DM daily. A 600kg cow can eat 21kg DM daily if offered to her.
Focus on providing an energy-dense diet throughout the breeding season. Typically, cows are at peak milk yield during the month of May, so they are also at peak energy demands. Cows grazing will be offered 16-17kg DM daily, but if their requirement is 21kg DM, then this energy gap should be filled with concentrates. Feed 4-5kg of concentrate if required in order to meet the cows DM intakes. If your cows have a higher DM intake, the use of buffer feeding may be required to meet their energy demands.
During mid-lactation, the cow increases her DM intake from grass and receives less from supplementary feeding. It is important to ensure that the correct levels of minerals and cal-mag, are still in the diet. Ideally, the feeding rate of the parlour concentrates should have the correct pro rata levels of minerals.
As the level of concentrates decreases in the parlour, it is worthwhile to manually weigh what is in a 'pull' in the parlour to ensure correct calibration. In order to avoid grass tetany while grazing, a feeding rate of 1.1kg
in the parlour requires 5 per cent cal-mag, a 2.25kg feeding rate requires 2.5 per cent cal-mag inclusion and 4.5kg requires 1.25 per cent cal-mag per tonne. The vital role minerals play in the resumption of cyclicity, and successful breeding of the mid-lactation cow cannot be overlooked. During breeding season we want a healthy immune system and a display of strong heat for cows. Deficiencies in certain trace minerals can be related to infertility if not dealt with early. For example, anoestrus behaviour and silent heats in the herd are linked to deficiencies in copper and manganese. So supplementation is a must, and organic forms are preferred, since they are more bioavailable for absorption and have fewer interactions with antagonists. The benefits are numerous. Organic selenium has been shown to significantly reduce incidences of metritis and reduced services per conception (Agovino, 2011).
Copper plays a vital role in improving fertility. Ideally, use an organic form of copper, such as Bioplex copper, in your feed throughout the breeding season. Organic minerals have a greater uptake in the cow’s small intestine in comparison to inorganic minerals.
The use of an organic selenium such as Selplex has been shown to help improve the cow’s immunity overall. Cows and calves fed with Bioplex calved 42 days earlier and produced an extra 170L of milk in the first 100 days. These types of results demonstrate the value of optimising your feed programme by including trace minerals. All in all, a healthy immune system is the core to having a successful breeding season. Minerals on their own are not a silver bullet but will help during breeding season. It is worth paying attention to the type of mineral being offered to breeding animals to put the best foot forward this breeding season.