Effects of restricted feeding of prepubertal ewe lambs on growth performance and mammary gland development

Abstract

The aim of this study was to determine the effects of restricted feeding before puberty on growth performance and mammary gland development in replacement ewe lambs. At weaning, 72 Dorset ewe lambs were assigned to one of the three diets: an ad libitum control diet with medium-quality forage (MQF; diet A-MQF); a restricted diet with the same forage as A, but less feed concentrate (diet R-MQF); or a high-quality forage (HQF) diet (diet F-HQF). The quantity of concentrate offered to the group R-MQF and F-HQF ewe lambs was adjusted to obtain 70% of the control ewe lambs' growth rate. The diets were offered for 75 days after weaning to cover the allometric phase of mammary gland development. During this period, average daily gain (ADG) was 223 and 229 g/day for groups R-MQF and F-HQF, respectively, compared to 305 g/day for group A-MQF ( P , 0.0001). At the end of this period, 28 ewe lambs were slaughtered and their mammary gland was collected. Parenchymal fresh tissue weight tended to be higher for groups R-MQF and F-HQF compared to group A-MQF ( P 5 0.09). Stroma weight was greater ( P , 0.05) for the group A-MQF ewe lambs than for those in the other treatments. Total DNA and total protein in parenchymal tissue tended to be greater for groups R-MQF and F-HQF ( P 5 0.09 and P 5 0.07, respectively). Dry fat-free tissue was greater for groups R-MQF and F-HQF ( P , 0.05). The remaining ewe lambs were fed the same haylage and barley diet until their first lambing. During this period, compensatory growth was observed. ADG was greater ( P , 0.01) for groups R-MQF and F-HQF than for group A-MQF, and feed conversion was improved ( P , 0.01) for groups R-MQF and F-HQF compared with the control, whereas the dry matter intake was similar for all groups. Live body weight, loin eye depth and backfat depth at breeding and around lambing were similar for all groups. The results of this study suggest that restricted feeding before puberty improves mammary gland development without compromising growth performance in ewe lambs.

Effects of restricted feeding of prepubertal ewe lambs on reproduction and lactation performances over two breeding seasons

“…Accordingly, plane of nutrition during gestation did not affect subsequent milk production in lambs (Umberger et al, 1985) and heifers (Lacasse et al, 1993). In a companion paper (Villeneuve et al, 2010), we reported that the mammary gland of restricted ewe lambs, groups R-MQF and F-HQF, was more developed than that of group A-MQF ewe lambs. Thus, the lower milk yield reported in this study supports the hypothesis of reduced mammary gland development.…”

“…The diets were offered for 75 days after weaning to cover the allometric phase of mammary gland development that occurred between 2 and 5.5 months of age according to Anderson (1975) and Johnsson and Hart (1985). After the restricted period, the animals had enough time to make a compensatory growth and reached ideal weight for breeding at 8 months of age (Villeneuve et al, 2010).…”

“…Feed restriction is reported to have effects on the growth of replacement ewe lambs (Villeneuve et al, 2010). Briefly, ADG was 223 and 229 g/day for groups R-MQF and F-HQF, respectively, compared to 305 g/day for group A-MQF (P , 0.0001) during the allometric phase of mammary gland growth.…”

“…The negative effect of rapid weight gain and fattening during early rearing on mammary gland development and lactation performance in replacement dairy heifers is well documented (Sejrsen, 1978;Sejrsen et al, 1982;Valentine et al, 1987;Mä ntysaari et al, 1995;Meyer et al, 2006). Accelerated gain before puberty reduces mammary secretory tissue in dairy heifers (Sejrsen et al, 1982) and in ewes (Zidi et al, 2007;Villeneuve et al, 2010). It also increases fat deposition in the mammary gland in heifers (Capuco et al, 1995;Charles et al, 1999) and in ewes (Johnsson et al, 1986; -E-mail: Lacassep@agr.gc.ca Peclaris et al, 1994Peclaris et al, , 1997Villeneuve et al, 2010).…”

“…Accelerated gain before puberty reduces mammary secretory tissue in dairy heifers (Sejrsen et al, 1982) and in ewes (Zidi et al, 2007;Villeneuve et al, 2010). It also increases fat deposition in the mammary gland in heifers (Capuco et al, 1995;Charles et al, 1999) and in ewes (Johnsson et al, 1986; -E-mail: Lacassep@agr.gc.ca Peclaris et al, 1994Peclaris et al, , 1997Villeneuve et al, 2010). Restricted feeding in the prepubertal period improves milk production in the first lactation in dairy heifers (Foldager and Sejrsen, 1991;Peri et al, 1993;Hohenboken et al, 1995;Van Amburgh et al, 1998;Lammers et al, 1999;Radcliff et al, 2000) and in dairy ewes (Zidi et al, 2005).…”