Feeding a high-fat diet may increase the percentage of heifers pubertal by the start of the breeding season. But, the diet effect interacts with heifer breed, so the response may depend on breed, say researchers at the USDA Agricultural Research Service (ARS).
The study found heifers with a low-fat body composition may have a different dietary fat requirement than heifers with a greater body fat composition.
In a 162-day feeding period, feeding 4.4% dietary fat increased the percentage of Piedmontese-sired heifers pubertal at the start of breeding by 21.4% (compared to those fed 1.9% dietary fat). For Hereford-sired heifers fed 4.4% dietary fat, the increase was only 1.9%. And, for Limousin-sired heifers, the percentage actually decreased 9.3%.
Other studies suggest a feeding period of approximately 60 days before the beginning of the breeding season may be more effective in improving reproduction in replacement heifers.
For more information contact Robert Bellows, ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, MT, 406/232-4970.
For calves born early in cold climates, blankets may be beneficial for improving average daily gain, according to researchers at North Dakota State University (NDSU).
Forty-eight cow/calf pairs were used to test the usefulness of wool-polyester blend blankets in improving weight gain and health of newborn calves. Fed the same diets and penned together in dry lots with barn access, the animals were either blanketed 12 hours post-partum or not at all. The four-period trial ran from January through February 1999.
To test environmental differences attributable to differing birth dates, blanketed calves were paired with a non-blanketed counterpart with a similar birth date.
Blanketed calves gained faster than non-blanketed calves, but the improvement decreased from 7.7% in the first period to 4.7% in the fourth period.
Blankets may improve weight gain by decreasing the amount of energy expended to maintain body temperature, and that spares more energy for tissue synthesis and growth.
One non-blanketed calf and four blanketed calves were treated for pneumonia, which was more apparent in blanketed calves when the daily high temperature exceeded 32F.
For more information contact Greg Lardy, NDSU, Fargo, ND 701/231-7660 or e-mail him at [email protected] nodak.edu.