Nutritionally altering weight gain patterns of pregnant heifers and young cows changes the time that feed resources are offered without any differences in production

• Published in: Journal of animal science 2005-04, Vol.83 (4), p.916-926
• Main Authors: Freetly, H. C, Ferrell, C. L, Jenkins, T. G
• Format: Article
• Language: English
• Subjects: Angus; Animal Feed; Animal Husbandry - methods; Animal Nutritional Physiological Phenomena; Animal productions; Animals; Biological and medical sciences; birth weight; Body Weight - physiology; calves; calving; Cattle - growth & development; Cattle - physiology; corpus luteum; cow feeding; cows; crossbreds; Eating - physiology; Energy Metabolism - physiology; Feed and pet food industries; Female; female fertility; Fertility - physiology; Food industries; Fundamental and applied biological sciences. Psychology; heifers; Hereford; lactation; liveweight gain; Parity; parity (reproduction); Pinzgauer; Pregnancy; pregnancy rate; Random Allocation; Red Poll; restricted feeding; Terrestrial animal productions; Time Factors; Vertebrates; weaning weight; Weight Gain - physiology
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/2005.834916x

We hypothesized that feed resources could be deferred to a later time in the production cycle without a decrease in fertility or weight of calf produced in heifers and young cows. One-hundred and thirty-one MARC III (four breed composite: [1/4] Hereford, [1/4] Angus, [1/4] Red Poll, and [1/4] Pinzgauer) heifers were divided into three treatments: M-M-M-M (n = 46), L-H-M-M (n = 41), and L-L-L-H (n = 44). The experiment consisted of four feeding periods. Period 1 was 94 to 186 d of gestation, and heifers were fed a moderate (M) or low (L) level of feed. Period 2 was 187 d of gestation to parturition, and heifers were fed moderate, high (H), or low levels of feed. Period 3 was from parturition through 27 d of lactation, and heifers were fed moderate or low levels of feed. Period 4 was from 28 d to approximately 63 d of lactation, and heifers were fed moderate or high levels of feed. Females remained within treatments through their first parity (heifers) and second parity (cows). Feed intake of L-H-M-M and M-M-M-M treatments did not differ from each other either as heifers (P = 0.23) or as second-parity cows (P > 0.59). The L-L-L-H heifers ate less feed than L-H-M-M and M-M-M-M heifers (P < 0.001), and second-parity L-L-L-H cows ate less feed than second-parity L-H-M-M and M-M-M-M cows (P < 0.002). In the first parity, treatments did not differ in the percentage of calves weaned (P = 0.11), weight of calf weaned (P = 0.50), or percentage of cows diagnosed pregnant (P = 0.29) with a second calf. In the second parity, treatments did not differ in the percentage of calves weaned (P = 0.77), weight of calf weaned (P = 0.63), or percentage of cows expressing a corpus luteum at the start of breeding for their third calf (P = 0.21). Our findings suggest that timing nutrient availability to heifers and primiparous cows can be used to change the time that feed resources are used.