Impact of shade use during gestation and lactation: performance responses of ewes and lambs in a tropical climate

Abstract

Heat stress in sheep affects not only physiological and behavioral parameters but also productive performance. This study evaluated the effects of the presence or absence of shade during the final third of gestation and lactation on the productive performance of ewes and their lambs. The experiment was conducted at the Center for Good Management Practices for Small Ruminants (CePRum) of the FAZU school farm in Uberaba, MG, Brazil, using twenty-three ewes in the final third of pregnancy (55 ± 5 kg, 36 ± 6 months of age, Body Condition Score (BCS) 3–3.5), randomly distributed into two treatments: SET (paddocks without shade; N = 11) and SAT (paddocks with 70% shade protection; N = 12). At birth, 31 lambs (15 males and 16 females; SET: 7 M and 9 F; SAT: 8 M and 7 F) were identified and kept with their mothers. For all animals, the following variables were analyzed: body weight (digital scale with 0.1 g precision) and BCS, using a 1 to 5 scale (1 = very thin, 5 = very fat). For ewes, measurements were taken 30 days pre-partum and at 30 and 60 days post-partum, and for lambs, measurements were taken at birth and at 30 and 60 days of age. Data were analyzed using a completely randomized design, employing ANOVA (GLM procedure) and Student's t-test (5% significance) for treatment comparisons (SET vs. SAT), after normality checks (Shapiro-Wilk), using RStudio software. SAT group ewes exhibited superior pre-partum BCS (P < 0.05) but lost more BCS points throughout lactation (P < 0.05) than the SET group. Although sun exposure did not affect the body weight of the animals in this study, it may have influenced body reserve deposition in sun-exposed ewes and possibly greater nutrient utilization for lactation in ewes with access to shade.