Effect of late gestational feed restriction and glucogenic precursor on behaviour and performance of Ghezel ewes and their offspring

Restricted maternal nutrition and supplementation of propylene glycol, monensin sodium and rumen-protected choline chloride during late pregnancy does not affect muscle fibre characteristics of offspring

BACKGROUND

Grazing in arid and semi-arid regions faces pregnant ewes with feed restrictions and hence affects the offspring muscle fibre characteristics. Using feed additives that enhance nutrient availability during foetal muscle development is expected to alter offspring skeletal muscle characteristics.

OBJECTIVES

This study evaluated the effect of maternal restricted nutrition and supplementation of propylene glycol, monensin sodium and rumen-protected choline chloride on lamb's muscle fibre characteristics.

METHODS

Forty-eight Ghezel ewes were randomly allocated to one of six diets (N = 8) during the last 6 weeks of gestation: ad libitum feed intake (AL); restricted feeding (RF); restricted feeding containing propylene glycol (PG); restricted feeding containing propylene glycol and monensin sodium (MS); restricted feeding containing propylene glycol and rumen-protected choline chloride (RPC); restricted feeding containing propylene glycol, monensin sodium and rumen-protected choline chloride (PMC). The muscle samples were obtained from the semitendinosus muscle of 2-week-old male lambs (n = 5/treatment) via biopsy and were stained and classified as fibre types I, IIA and IIB.

RESULTS

Pre-parturient maternal feed restriction and administration of propylene glycol, monensin sodium and rumen-protected choline chloride had no significant effect on fibre-type composition, fibre density of muscle, muscle cross-sectional area and volume density of fibres (p > 0.05).

CONCLUSIONS

Either maternal dietary restriction or supplementation of nutrient flux-involved additives during late pregnancy did not alter muscle fibre development and had no short-term effects on muscle properties of the resulting offspring as myogenesis occurs in early and mid-gestation, not late gestation. Therefore, maternal nutrition may not be a problematic issue in sheep production in arid and semi-arid areas.

Feed restriction around parturition does not affect colostrum immunoglobulin G concentration in dairy fat-tailed sheep but does affect performance and blood metabolites in newborn lambs

This study aimed to investigate the effect of prepartum and postpartum feed restriction of fat-tailed dairy sheep on colostrum IgG concentration, and performance and blood metabolites of newborn fat-tailed lambs. Twenty fat-tailed dairy sheep were randomly allocated into control (Ctrl; n = 10) and feed restriction (FR; n = 10) groups. The Ctrl group received a diet that met 100% of energy requirements, both prepartum (from wk -5 to parturition) and postpartum (from parturition to wk 5). The FR group received a diet equivalent to 100, 50, 65, 80, and 100% of the energy requirements in wk -5, -4, -3, -2, and -1 relative to parturition, respectively. After parturition, the FR group received a diet equivalent to the 100, 50, 65, 80, and 100% of the energy requirements in wk 1, 2, 3, 4, and 5, respectively. At birth, lambs were assigned to their dam's experimental group. Both the Ctrl lambs (n = 10) and the FR lambs (n = 10) were allowed to suck colostrum and milk from the dams. Colostrum samples (50 mL) were collected at parturition (0 h) and then at 1, 12, 24, 36, 48, and 72 h postpartum. Blood samples were collected from all lambs before suckling colostrum (0 h) and then at 1, 12, 24, 36, 48, and 72 h after birth and weekly until the end of the experimental period (i.e., wk 5 relative to birth). The data were evaluated using the MIXED procedure of SAS (SAS Institute Inc.). The model included feed restriction, time, and the interaction feed restriction × time as fixed effects. The individual lamb was set as a repeated subject. Variables measured in colostrum and plasma were considered dependent variables, and significance was set at P < 0.05. Prepartum and postpartum feed restriction in fat-tailed dairy sheep did not affect colostrum IgG concentration. Consequently, no differences in blood IgG concentrations were observed in the lambs. In addition, the prepartum and postpartum feed restriction experienced by fat-tailed dairy sheep caused decreased body weight and milk intake in lambs from the FR group compared with the Ctrl group. Feed restriction also promoted increased concentration of blood metabolites such as triglycerides and urea in FR lambs compared with control lambs. In conclusion, prepartum and postpartum feed restriction in fat-tailed dairy sheep did not affect either colostrum IgG concentration or blood IgG concentration of the lambs. However, prepartum and postpartum feed restriction decreased lamb milk intake and, therefore, lamb body weight gain during the first 5 wk after birth.

The Onset of Maternal Behavior in Sheep and Goats: Endocrine, Sensory, Neural, and Experiential Mechanisms

In sheep and goats, the onset of maternal behavior at parturition is characterized by a first phase called maternal responsiveness during which the mother is attracted to any newborn. In a second phase, called maternal selectivity, the mother establishes a selective bond with her young so that she only accepts it at suckling. After a description of the behavioral expression of both phases, this chapter reviews the physiological, sensory, and neural mechanisms involved. These two behavioral processes are synchronized with parturition by the vaginocervical stimulation induced by the expulsion of the newborn. Olfactory cues provided by the neonate are involved in maternal responsiveness and selectivity. Oxytocin supported by estrogens is the key factor for maternal responsiveness. The neural network involved in maternal responsiveness is mainly hypothalamic and is different from the circuitry involved in selectivity, which mainly concerns olfactory processing regions. Visual and auditory cues are necessary for offspring recognition at a distance. This multisensory recognition suggests that mothers form a mental image of their young. Maternal experience renders mothers more responsive to maternally relevant physiology and to young-related sensory inputs.

Prepartum and Postpartum Feed Restrictions Affect Blood Metabolites and Hormones Reducing Colostrum and Milk Yields in Fat-Tailed Dairy Sheep

Simple Summary

Despite the fact that fat-tailed sheep raised for meat production are well known for being resilient to harsh environmental conditions such as pasture scarcity or low-quality feedstuffs, no studies regarding feed restriction have been performed on fat-tailed dairy sheep. In this study, prepartum feed restriction from week −5 to week −1 relative to parturition did not affect body weight. Similarly, postpartum feed restriction from week 1 to week 5 relative to parturition did not affect body weight. However, both prepartum and postpartum feed restrictions affected blood metabolites and hormones, which decreased both colostrum and milk yields postpartum.

Abstract

This study aimed to investigate the effect of prepartum and postpartum feed restriction on body weight (BW), blood metabolites, and hormones as well as colostrum and milk yields and compositions in fat-tailed dairy sheep. In this study, 20 multiparous and pregnant ewes were randomly allocated to either the control (Ctrl; n = 10) or the feed-restricted (FR; n = 10) groups from week −5 to week 5 relative to parturition. Despite dry matter intake being decreased in the FR group compared to the Ctrl throughout both prepartum and postpartum periods, no differences in BW were detected between groups in any of the studied periods. Feed restriction increased both free fatty acids and beta-hydroxybutyrate concentrations during both prepartum and postpartum periods. Similarly, feed restriction increased triglyceride concentration postpartum. Additionally, feed restriction increased insulin and growth hormone and decreased prolactin concentrations during both prepartum and postpartum periods. Feed restriction caused a decreased colostrum yield and a relative increase of the main colostrum components in the FR group. Similarly, milk yield decreased in the FR group compared to the Ctrl group, although milk components were not affected. In conclusion, feed restriction did not affect BW but decreased colostrum and milk yield in fat-tailed dairy sheep.