The Cow-Calf Manager:
Add Fat to Late Gestation Cow Diets -- Cottonseed May Help

Livestock Update, January 2000

John Hall, Extension Animal Scientist, Beef, Virginia Tech

Cows must calve in good body condition in order to have healthy calves and breed back quickly. However, many cows in Virginia are entering the last part of gestation in less than ideal body condition. Research from Kansas indicates that calves from thin cows, especially heifers, will be smaller and weaker than cows gaining weight in the last 60 days before calving. Although calves on restricted energy diets are 5 to 8 lbs. lighter than calves from well-fed cows, there is no difference in the number of calves that had to be pulled.

More of calves from underfed heifers and cows die at birth or between birth and weaning (Table1). Calves from underfed cows are more likely to get sick. Any dead calf is an automatic $400 to $500 or greater loss. Any calf that gets sick in the first 45 days will weigh 35 to 40 lbs less at weaning than a calf that didn't get sick.

Weak Calf Syndrome is a protein and energy deficiency in newborns. Calves are weak and have trouble maintaining body temperature. Calves born to thin cows are at greatest risk. Weak calf syndrome can be prevented by proper cow nutrition during late pregnancy. Extra care and tube feeding of these calves may save some of them.

Table1. Effect of energy level in late gestation on calf weight and survival

	Energy Level
	High		Low
	Birth	Weaning	Birth	Weaning
Average weight, lbs	67	321	59	293
% Survival	100	100	90	71
Lbs. of calf / heifer	67	321	53	203

Exposure. Exposure to cold and precipitation can kill newborn calves rapidly. A study of 87,285 calves born at Clay Center, Nebraska demonstrated that even without rain or snow the percentage of calves that die due to exposure increases rapidly below 50 degrees F (See graph). A little rain or wet snow makes the problem even worse. As little as 0.10 inches of precipitation on the day the calf is born can mean trouble. Calves from 2-year-old heifers are at the greatest risk.

The effects of exposure can be minimized if care is taken to ensure calves nurse soon after birth. In addition, during extremely cold or wet conditions calves may need shelter for the first 24 to 48 hours of life. Chilled calves should be brought in for warming and assisted in nursing if necessary. The new "calf blankets" may provide some advantage in cold dry conditions. Extra attention to newborn calves during bad weather can pay big dividends.

Extra energy from fat. Recently, researchers from Montana fed cows safflower seeds to add extra fat to the diet during the last 60 days of gestation. Other cows in the study were fed the same amount of energy as cows fed safflower seed, but just less fat. Calves from cows fed safflower seed were better able to survive in the cold. In addition, these calves had more glucose (blood sugar) so they had extra energy to keep warm and to get up and nurse. Cows fed safflower seed also came into heat sooner after calving.

We are presently experimenting with feeding whole cottonseed, as a source of fat, to cows and heifers in late gestation. Although experimental, feeding cows 4 to 5 lbs. of whole cottonseed per day during the last 60 days of pregnancy may increase calf survival. However, diets should not contain more than 5% fat or rumen function will be impaired. The extra energy and protein provided should be especially beneficial to thin cows. We will have more information after a field trial this March.

Cottonseed is expensive relative to other feeds, so you may want to just increase the energy intake of your cows by feeding 5 to 6 lbs. of corn or corn gluten during the last 60 days of gestation. This is especially important for thin cows and heifers.

Cottonseed may be worth a try this winter for thin cows and heifers. However, regardless of what you choose to feed, be sure to get more energy in your thin cows and heifers during the last two months of pregnancy.

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