PSII-9 Preliminary Investigation of Nutrient Challenge During Pregnancy on Wether Lamb Development, Growth, and Performance from Birth to Harvest

Abstract

Inadequate nutrition during gestation has been shown to impair growth and metabolism of affected offspring and can predispose them to lifelong inefficiency and poor performance. Development throughout preweaning has been studied and compared to carcass performance; however, the impact of nutrient challenge during gestation on post weaning growth, efficiency, and nutrition utilization is not well known. Thus, our objective was to investigate the impacts of maternal nutrient restriction in late gestation on wether lambs' lifelong performance, from birth through harvest. We hypothesized that lambs from nutrient restricted dams would have reduced growth efficiency, taking longer to reach market weight and yielding altered body and carcass composition. Twenty-two bred yearling ewes were fed a diet meeting 100% of National Research Council (NRC) requirements until the 110th day of gestion (dGA). From 110 dGA until lambing occurred, ewes were either maintained on a diet meeting 100% of NRC requirements (n = 10) or reduced to a diet of 65% of NRC requirements (n = 12). Beginning at birth, body weight and morphometrics were collected weekly for control (CONT; n = 4) and treatment (NR; n = 5) wether lambs. At approximately 71 days of age, wethers were weaned and placed into individual pens to simulate a controlled feedlot setting. Wether lambs were fed a commercial lamb finishing diet ad libitum and orts were collected to evaluate feed efficiency and growth. At 115 days of age, wethers were placed in metabolism crates for 5 days to allow for total collection or urine and feces in order to evaluate nutrient balance. Birthweight, weaning weight, and morphometrics did not differ between NR and CONT lambs from birth until weaning. However, there was a tendency (P < 0.10) for a slower rate of gain from birth until weaning in NR lambs compared to their CONT counterparts. Current research in feedlot performance and digestibility is ongoing; however, thus far there are no differences in feed intake or average daily gain. These data suggest that a moderate nutrient challenge in the last month of gestation is not substantial enough to induce adaptive changes that result in differences in postnatal growth and performance.