Johnstown Castle targets diets and genetics to ease herd infertility issues
Published 01/11/2011 | 05:00
Our breeding programme really kicks off from the time our cows go dry. They have a relatively long dry period of up to 60 days, which can lead to cows getting over conditioned, especially if they are on good grass. One of the ways that we try to restrict the chance of this happening is by letting the dry cows mop up grazing after the milking herd.
Generally, we aim to have them calving down with a body condition score of 3.25. This year, we switched to a lower crude protein concentrate for the high input cows. Previously they were on a 17pc protein nut, but we lowered that to 16pc this year. It probably cost us 1-1.5kg of milk per cow per day but I think it left them with a flatter milk curve which minimised the amount of condition that they lost after calving.
Calving starts around the first or second week of September and continues right through until December 10. The vast majority will be calved by November when we start our breeding programme. We have tried to intensify our pre-breeding heat detection programme by recording any heats we see for about three weeks before we start serving cows. We serve cows for 13 weeks, which of course is a double-edged sword in that we keep a tight calving period and a calving interval of 380 days. The downside is that we have a reasonably high empty rate of 20pc at the end of the year. Most autumn calving herds will roll these on into the spring calving half of the herd but the economics of doing this aren't fully understood. We're going to do some research into that over the coming years.
Our submission rates for the first 30 days of the breeding season are good, usually 85-90pc. We observe and record all heats at morning milking, during the day and again at 9pm at night. Tail-painting is our main tool. We also have had Dairymaster's Moo Monitor system here for the last three years and while it is definitely a benefit, I'd be slow to move away from the combination of tail painting and observation.
Despite this good submission rates, we've struggled to get our conception rates any higher than 43-50pc for first or second services. We're trying to address this through a combination of tinkering with the diet and, long term, breeding for better fertility. We're only selecting bulls with a fertility sub-index of €100 or higher. At the same time, we want a bull that is positive for fat and protein percentages and giving us 150kg in milk to maintain the herd average yield at over 7,000kg. These criteria tend to narrow the bull pool to bulls in the top 10-15pc. Most straws will be costing €16-20. We'd also be keeping an eye on type and the bloodlines to make sure there is the minimum of cross-breeding. Last year we used a good bit of UPH, SOK and LLK. We're also trying to improve the record keeping of other events that impact on fertility such as calving, where we score the calving from 1-4 for difficulty, with 4 a calving that requires veterinary assistance.
Retained placentas are also recorded and all the cows are scanned before breeding starts. This costs about €2.50 a cow but I think it's a good investment. Dirty or aneostrus cows are then washed out or put on a CIDR programme.