Progesterone administration reduces the behavioural and physiological responses of ewes to abrupt weaning of lambs

Abstract

Abrupt weaning, a usual management in sheep productive systems, may provoke behavioural and physiological responses indicative of stress in ewes and lambs. Progesterone (P4) has anxiolytic and sedative effects through the union of its metabolites that contain 3a-hydroxyl group to the g-aminobutyricacid A receptor. Our first aim was to determine whether P4 administration reduces the behavioural and physiological responses of ewes to abrupt weaning of lambs. A complementary aim was to determine whether P4 treatment affects the milk yield and composition of ewes, and the BW of their lambs. In experiment 1, seven ewes received P4 treatment for 32 days (group E1-P4), and eight ewes remained as an untreated control group (group E1-C). BW of the lambs was recorded during P4 treatment. Lambs were weaned at 59 days (Day 0 5 weaning). The main behaviours of the ewes before and after weaning were recorded using 10 min scan sampling. The ewes' serum total protein, albumin and globulin concentrations were measured before and after weaning of the lambs. In experiment 2, milk yield and composition were determined in two different groups of six ewes treated with P4 (group E2-P4) for 16 days and in five untreated controls (group E2-C). The BW of lambs increased with time ( P 5 0.001) in both groups and did not differ. The percentage of observations in which the ewes were seen pacing on Day 0 was greater in the E1-C group than in the E1-P4 group ( P 5 0.0007). Similarly, the percentage of observations in which the ewes were recorded vocalizing on Day 0 was greater in the E1-C group than in the E1-P4 group ( P 5 0.04). The percentage of observations in which E1-C ewes were recorded lying did not change from Days 0 to 1; however, it increased in E1-P4 ewes. Total serum protein concentration did not change in E1-P4 ewes from Days 0 to 3, although a decrease was seen in E1-C ewes ( P 5 0.04). Serum globulin concentration was greater in E1-P4 ewes on Day 3 than in E1-C ewes (P 5 0.0008). In experiment 2, there were no differences between E2-P4 and E2-C ewes in terms of milk yield, protein, fat and lactose content. Progesterone administration reduced the behavioural and physiological responses of ewes to abrupt weaning of lambs, and this effect was not mediated by changes in milk yield and composition, or by lambs' BW.

Low pasture allowance until late gestation in ewes: behavioural and physiological changes in ewes and lambs from lambing to weaning

“…The greater behavioural changes recorded in HPA lambs after weaning, which led to high energy expenditure, was not enough to provoke different BW. Overall, weaning was a stressful situation for lambs; this problem demands the development of specific research to minimize welfare problems associated with this management (Freitas-de-Melo et al, 2013;Pascual-Alonso et al, 2015). Figure 5 Percentage (mean ± SEM) of observations in which lambs were observed (a) pacing, (b) vocalizing, (c) standing, (d) walking, (e) lying down, (f) grazing and (g) ruminating before and after weaning of lambs reared by ewes that grazed on high ( ) or low ( ) native pasture allowances from 23 days before conception until 122 days of gestation.…”

“…All ewes were manually milked on days 32, 41 and 54 after lambing, and milk yield was estimated according to Freitas-de-Melo et al (2013). In brief, lambs were shifted to another paddock and all ewes were injected i. m. with 5 IU of oxytocin (Hipofamina, Laboratorios Dispert, Montevideo, Uruguay) and milked completely; 4 h later, ewes were milked again with the same protocol and joined again with their lambs.…”

“…The behavioural response involves an increase in the frequency of vocalizations, time pacing and standing, and a reduction in the time lying down, grazing and ruminating (Orgeur et al, 1998;Damián et al, 2013;Freitas-de-Melo et al, 2013). The decreasing in feeding and resting behaviours, together with the increase in physical activity, probably results in a loss of BW of the lambs.…”

Progesterone pretreatment increases the stress response to social isolation in ewes

“…4,5 In ewes, P4 administration reduces the behavioural and physiological responses to weaning, a strong stressor. 6 On the other hand, it has also been reported that reduction of P4 in rodents -as is observed immediately after luteolysis − has anxiogenic effects through a decrease in the inhibitory effect of GABA. 7 Thus, the animals have an increased sensitivity to stressors, as for example the open field test.…”

Destete artificial en ovinos: respuesta de estrés y bienestar animal. Revisión

“…La intensidad de la respuesta al destete artificial, y las consecuencias del mismo sobre la producción y el bienestar de los animales varía de acuerdo a la intensidad del vínculo con la madre durante el período anterior al destete, la edad de los corderos, el sexo de las crías, la raza y la alimentación de las ovejas durante la gestación y la lactancia (5,6,7) . En ovinos se ha estudiado la respuesta productiva y los efectos negativos producidos por diferentes tipos de destete: abrupto, progresivo, en etapas, y alambrado de por medio (colocación de ovejas y corderos separados por un alambrado durante varios días antes de la separación definitiva) (6,8,9,10) . De acuerdo a una serie de trabajos realizados, el destete abrupto a pesar de ser el más utilizado, y el destete realizado con alambrado de por medio, son los que generan mayores respuestas de estrés al Sheep are characterized by a highly selective mother-lamb bonding, which is set immediately after lambing (1) .…”