|Taylor, Joshua - Bret|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2008
Publication Date: 4/25/2008
Citation: Swanson, T.J., Hammer, C.J., Luther, J.S., Carlson, D.B., Taylor, J.B., Redmer, D.A., Neville, T.L., Reed, J.J., Caton, J.S., Vonnahome, K.A. 2009. Effects of gestational plane of nutrition and selenium supplementation on mammary development and colostrum quality in pregnant ewe lambs. Journal of Animal Science. 86:2415-2423. Interpretive Summary: We examined the effects of nutritional plane (energy and protein) and selenium supplementation on colostrum quality and mammary development in pregnant Rambouillet ewe lambs. Level of dietary selenium did not affect ewe lamb productivity. However, based on the results, we found that providing excessive dietary energy and protein from mid to late pregnancy negatively affected colostrum yield and composition at lambing. Furthermore, we found that the size of the mammary gland is not a good predictor of colostrum yield or quality because the mammary gland weight was similar between ewes fed adequate nutrition and ewes that were overnourished during mid and late pregnancy. In conclusion, providing supplemental energy and protein in excess of the recommended nutrient requirements during mid to late pregnancy may be potentially detrimental to ewe lamb productivity.
Technical Abstract: To examine effects of nutritional plane and selenium (Se) supplementation on colostrum quality and mammary development, individually fed, pregnant Rambouillet ewe lambs were allotted randomly to 1 of 6 treatments in a 2 x 3 factorial arrangement. Main effects included dietary Se level which began at breeding (d = 0) [adequate Se (ASe, 9.5 Gg/kg BW) vs. high Se (HSe, 81.8 Gg/kg BW)], and plane of nutrition which began at d 50 of gestation [60% (RES), 100% (CON), and 140% (HIGH) of requirements]. Upon parturition lambs were immediately separated from dams and weighed. Three hours after lambing, colostrum yield was determined and samples were obtained for components and IgG analysis. Ewes were slaughtered within 24 h of parturition, and mammary tissues were collected for determination of alveolar secretory epithelial cell proliferation index and luminal area. Gestation length was reduced (P <0.01) in HIGH ewes compared to RES and CON ewes. Although birth weights were reduced (P < 0.01) in RES and HIGH compared with CON ewes, there was little effect of diet on placental size. Mammary gland weight was reduced (P < 0.05) in RES compared to CON and HIGH, which were similar. However, when expressed as g/kg BW, mammary gland weight in HIGH ewes was less (P = 0.03) compared to RES and CON. Colostrum weight and volume were reduced (P < 0.01) in RES and HIGH ewes compared with CON. Although colostrum IgG concentration was greater in RES ewes compared to CON and HIGH, total IgG was lower (P = 0.06) in RES and HIGH compared to CON ewes. The percentage of alveolar cells proliferating was increased (P < 0.04) in HIGH compared with RES ewes, with CON being intermediate. Percentage of alveoli luminal area per unit tissue area was increased (P = 0.04) in RES compared with HIGH and CON ewes, which did not differ. Selenium had no effect (P > 0.15) on mammary gland weight, colostrum quantity, or IgG concentration in pregnant ewe lambs. Insufficient nutrition from mid to late pregnancy in ewe lambs altered colostrum quality and quantity, and reduced offspring birth weight, which may have negative implications for lamb health and survival during the early postnatal period.