WATER SHORTAGE INCREASES LATER EMBRYO DEATH
Water is an integral element of our daily industry. The current drought is having enormous adverse effects on both welfare of our livestock and stress placed on farm families. Milk production has dropped dramatically and the incidence of later foetal death has increased. This will ultimately increase the number of empty cows at the end of this breeding season.
Farmers are now faced with the challenges of managing daily herds where grazed grass was the sole ingredient of the diet to one where grazed grass has to be “rationed” and dietary supplementation of concentrates and silage is the norm.
Aside from this is the need for water by the cow in a high temperature environment. The demand for water increases dramatically as the temperative humidity index increases. As herd size increased over the past number of years there has been a concurrent upgrade in water supply and size of water troughs on farms. The current heat wave has clearly shown the implications of inadequate water supply on the farm.
Farmers have to now contend with the need to get cows in calf while milk production drops because of either inadequate water supply or reduced nutritional dietary supplementation. Our scanning records for the past month have revealed a dramatic increase in later embryonic deaths.
Embryo mortality beyond day 34 of gestation is primarily associated with either cows carrying twins or infectious diseases such as Neosporin or BVD. The current drought has increased the stress load on cows and with water supply being inadequate on many farms, has depressed the immune system resulting in poor inherent defence systems. These have resulted in diseases such as Neospora and IBR becoming active in the herd. These diseases will kill foetuses beyond day 34 of gestation. Scanning records reveal that this feature of later foetal death only occurred among cows bred after the 20th of May, which is linked to exposure to stressors imposed because of the current drought. Cows experiencing foetal death beyond date 34 of pregnancy will take up to 8 weeks to return to heat naturally. Your breeding programme for spring calving will be finished in 3 weeks’ time for most herds. Identify these cows carrying dead pregnancies now by scanning. Your vet can then administer prostaglandin to these cows, which will enable them to go back in calf within 2 to 4 days.
What can you do to reduce the adverse effect of this drought? Some farmers are frantically sinking new bore wells to create a better water supply. Place large water troughs close to the exit area from the milking parlour. Allow cows access to water troughs in other areas of the grazing platform where feasible.
Farmers are now feeding 6 to 8 kg of concentrates where grass is in short supply and the long range forecast suggests no rain until the end of July. This scenario does make economic sense in the realm of sustainability. Placing undue stress on your cows now will kill pregnancies between day 34 and 50 of age. There is a minimum financial gain of €650 for every cow that does not lose her pregnancy. Some farmers with access to rivers have started irrigation systems using sprinklers to increase grass growth. This is not feasible on most farms. It is difficult watching grass turn brown over large sections of land on sandy soils or shallow soil on upland farms
Farmers are now faced with second cut silage where grass has headed out prematurely because of heat stress. Feed value of this grass will decrease rapidly if not ensiled now. Alternatively farmers are either grazing their second cut silage ground or using zero grazing to feed directly to their cows. Your primary objective has to be the prevention of later embryo deaths by reducing the stress load on your dairy herd.
In conclusion, the current drought has refocused many farmers on their desire to increase dairy herd size. We cannot continue to run our business in the “red zone” where sustainable food production will not pertain.
Dr Dan Ryan is a bovine reproductive physiologist and can be contacted on www.reprodoc.ie
Article written by Dr. Dan Ryan for the Farming Independent for the 17th July 2018