Winter and spring precipitation are predicted to increase in the Midwest region of the United States, causing muddy conditions. In a previous experiment, Angus cows (8 per treatment) were paired based on initial body weight (BW) and one cow from each pair was randomly allocated to either the mud or control treatment. Though cows consumed the same amount of dry matter, cows in the mud treatment weighed 37.4 kg less than cows in the control treatment by day 269 of gestation. The objective of this experiment was to evaluate developmental programming effects of steers born to cows in the mud treatment (MUD; n = 7) or the control treatment (CON; n = 6). Steers were weighed at birth and then weekly from approximately 56 d of age until weaning and were subjected to a glucose tolerance test (GTT) and adrenocorticotropic hormone (ACTH) challenge after weaning. Steers were then placed in the feedlot for an 84-d growing phase and were weighed weekly and 12th rib back fat (BF) and ribeye area (REA) were imaged every 28 d using ultrasonography. Data were analyzed as a randomized complete block design with repeated measurements when appropriate (SAS 9.4). Although there was a 37.4 kg decrease in BW of cows by the end of gestation, there was no evidence of a pen treatment effect on calf birth weight (P = 0.60) or weaning weight (P = 0.99). Additionally, there was no evidence of a pen treatment × day effect for steer BW from birth to weaning (P = 0.67) or growing phase BW (P = 0.60). There was evidence of a treatment × day of growing phase effect (P = 0.02) for BF, such that CON steers had greater BF on day 28 of the growing phase; however, there was no evidence of a treatment × day effect for REA (P = 0.20). Furthermore, there was no evidence of a pen treatment effect for the growing phase average daily gain (P = 0.74), dry matter intake (P = 0.65), gain:feed (P = 0.48), plasma glucose concentration (P = 0.67) or plasma insulin concentration (P = 0.61) in response to the GTT, or plasma cortisol concentration in response to the ACTH challenge (P = 0.51). These results indicate that while mud increased net energy requirements for cows in the MUD treatment, there were no subsequent effects observed for steer BW, gain:feed, or response to glucose and ACTH during the growing phase.
Keywords: beef cow; calf growth; developmental programming; late gestation; nutrient restriction.
Predictions for the Midwest U.S. indicate that both winter and spring temperatures and precipitation will increase. These climatic changes could result in muddier conditions during winter and spring in the Midwest. It has previously been demonstrated that a muddy environment increases the net energy requirements of mature cow’s by approximately 3.9 Mcal/d. If cows are not provided this extra energy and are exposed to mud during late gestation, it is likely that this will cause an adverse environment for the conceptus that could result in compromised growth and metabolism later in life. This study evaluated the developmental programming effects after birth and into the growing phase with beef steers born to cows that were housed in a muddy environment during late gestation compared with steers born to cows that were housed in pens bedded with wood chips during late gestation. Based on the present results, the mature cows housed in the muddy conditions weighed approximately 37.4 kg less than cows housed in pens bedded with wood chips during late gestation, however, calf birth weight, postnatal growth, postnatal feed intake and gain:feed, and postnatal response to glucose and adrenocorticotropic hormone was not affected. This indicates that the mature cows were able to mobilize body stores and supplied the fetus with adequate nutrients during gestation without impairment of growth or postnatal response to glucose and adrenocorticotropic hormone.
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