By Peter Shipton, senior technical specialist, Kingshay
Very few producers would claim they are 100% happy with their herd fertility. Poor herd reproductive performance is a major cost for all dairy producers and one which many herds struggle to improve.
Extended days to first service and low conception rates lead to reduced farm milk output and increased vet and AI costs.
Higher culling rates are also a result of poor fertility, resulting in the loss of valuable genetics and the need for more replacements. In fact, Kingshay Dairy Manager data indicates that on average 27% of culling is directly related to fertility management.
It is widely believed poor fertility goes hand-in-hand with high yields, but this does not have to be the case (see graph below, which use data from Kingshay’s new Health Manager service).
Kingshay figures reveal services per conception has very little to do with milk yield a cow or herd size. It is important to note, though, that there is a large difference between farms with the best conception rates compared with the worst.
Analysing 100-day in-calf rates shows some lower-yielding herds perform exceptionally well, but this is certainly not the case for all herds at this level of production, with higher-yielding herds often having comparable levels of pregnancy.
Culling due to infertility ranges from 2% to 12% of the herd for 9000-litre herds and from 2% to 10% for 7000-litre herds. These rates fall to 2-4% for 5000-litre herds but it is clear there is potential for all herds to move closer to just 2% of the herd being culled for infertility.
For Kingshay costed herds, the cost of infertility for every litre produced ranges from less then 1p/litre to more than 5p/litre. This is unrelated to cow yield and is a reflection of on-farm fertility and nutrition management.
Herd infertility is a combination of cow, environment and people factors, but many of these are the same regardless of yield or herd size.
The key to maintaining good fertility in high-yielding herds is maintaining adequate nutrition. In particular:
• Good dry cow and transition cow feed management
• Maximising dry matter intakes (DMI)
• Minimising early lactation body condition loss, particularly in early lactation
The greatest fertility challenge for the high-yielding herd is in maintaining the correct energy balance and body condition score, particularly in early lactation. Controlling weight loss in early lactation, by maintaining an adequate energy density for the expected yield in the diet, is vital.
The rate of weight change rather than the condition score at time of service affects the cow’s ability to conceive. The table [above] shows the reduction in fertility resulting from different rates of change in body condition score.
A negative energy balance often occurs in early lactation as DMI struggles to meet the demands of production. This is why good transition cow management is essential to maintain cow health, prevent problems at calving and encourage feed intakes.
Monitoring cow performance and health in early lactation will give an early warning of potential fertility problems. Cows not reaching expected yields, low milk protein (<3.0%), high milk urea levels (>0.045%) and poor general health could all be indicating potential dietary problems so take advice from a good nutrition adviser.