title: Differential effects of maternal undernutrition between days 1 and 90 of pregnancy on ewe and lamb performance and lamb parasitism in hill or lowland breeds.
abstract: This study examined the hypothesis that responses of Scottish Blackface (BF, a hill breed) and Suffolk (SUF, a lowland breed) ewes to undernutrition between d 1 and 90 of pregnancy would differ. Over 2 consecutive breeding seasons, ewes (4 pens/treatment; 15 to 20 ewes/pen) were artificially inseminated and from d 1 to 90 after AI allocated to 0.75 (restricted; RES) or 1.0 (control; CON) energy requirements for ewe maintenance and fetal growth. From d 90 to term, all ewes were allocated feed to meet requirements for stage of pregnancy and expected litter size. On d 90, RES ewes had lighter BW (P = 0.001) and smaller BCS (P = 0.019) than CON ewes. Plasma NEFA concentrations were greater in RES than CON ewes (P = 0.048) at d 60 of pregnancy. Pregnancy length was longer for RES than CON ewes (P = 0.003). Lambs from SUF-RES ewes had lighter birth weights than SUF-CON lambs, but BF-RES lamb birth weights were not different from BF-CON lambs (interaction, P = 0.066). However, maternal undernutrition did not affect BW at weaning (P > 0.45). Between birth and 3 d of age, BF lambs maintained greater body temperatures (P < 0.001) and plasma concentrations of triiodothyronine (T3, P < 0.001) and thyroxine (P < 0.001) than SUF lambs. Lambs from RES ewes had greater concentrations of T3 (P = 0.026) than CON lambs, whereas these differences were greater between BF-RES and BF-CON lambs than between SUF-RES and SUF-CON lambs (interaction, P = 0.028). Maternal undernutrition did not affect lamb rectal temperature (P > 0.27). In yr 1 only, fewer lambs (P = 0.022) were reared to weaning by RES than CON ewes. Similarly, in yr 1 only, other strongyle fecal egg counts at weaning were greater in SUF-RES lambs than SUF-CON, BF-CON, or BF-RES lambs (interaction, P = 0.099). This experiment showed that lambs of a breed selected for lean tissue growth and normally maintained in a lowland environment were more affected by maternal undernutrition between d 1 and 90 of pregnancy than lambs of a hill breed managed in a more adverse environment.
authors.affiliation: Sustainable Livestock Systems, Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, UK. john.rooke@sac.ac.uk
authors.forename: J A
authors.initials: JA
authors.lastname: Rooke
authors.forename: J G M
authors.initials: JG
authors.lastname: Houdijk
authors.forename: K
authors.initials: K
authors.lastname: McIlvaney
authors.forename: C J
authors.initials: CJ
authors.lastname: Ashworth
authors.forename: C M
authors.initials: CM
authors.lastname: Dwyer
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001947:Breeding; D005260:Female; D020022:Genetic Predisposition to Disease; D006854:Hydrocortisone / Q000097:blood; D039382:Maternal Nutritional Physiological Phenomena; D010273:Parasitic Diseases, Animal / Q000235:genetics* / Q000378:metabolism; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012756:Sheep; D012757:Sheep Diseases / Q000235:genetics / Q000469:parasitology*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D015430:Weight Gain
chemical_list: D014284:Triiodothyronine; D013974:Thyroxine; D006854:Hydrocortisone