Feed restriction and supplementing with propylene glycol, monensin sodium and rumen-protected choline chloride in periparturient Ghezel ewes: Implications on production and performance of ewes and their offspring

Abstract

This study was conducted to evaluate the effects of supplementation of propylene glycol, monensin sodium and rumen-protected choline chloride to the late gestational restricted diet on milk production and composition, rumen fermentation and dry matter intake of ewes and their offspring performance. During the final trimester of pregnancy, 48 Ghezel ewes were randomly assigned to one of the 6 treatments: ad libitum feeding (CG, control); feed restriction (FR, 60% of ad libitum intake); feed restriction + propylene glycol (67 g/d) (FR-PG); feed restriction + propylene glycol + monensin sodium (30 mg/d) (FR-MS); feed restriction + propylene glycol + rumen-protected choline chloride (6 g/d) (FR-RPC); feed restriction + propylene glycol + monensin sodium + rumen-protected choline chloride (FR-PMC). Milk samples were collected during the first 4 weeks of lactation and analyzed for fat, protein and solids non-fat contents. Ruminal fluid was sampled on day 125 of pregnancy for the determination of volatile fatty acids and ammonia-nitrogen concentration. Dry matter intake of ewes was calculated daily according to the differences between feed provided and refused. The average daily gain of lambs was recorded until 30 days postnatal and weight on day 87 was considered as weaning weight. The data were analyzed in a completely randomized design using SAS v.9.3. The results showed that FR-RPC and FR-PMC ewes presented approximately a higher milk production (P < 0.05), milk protein and solids non-fat percentages (P < 0.01) than other ewes in almost all recording points. During the first and second weeks of lactation, the milk produced by FR ewes had the lowest fat percentage among all experimental groups (P < 0.0001). The lowest ruminal pH and ammonia-nitrogen concentration was found in FR and FR-MS ewes (P < 0.0001). Ewes in the CG and FR groups produced lower levels of total volatile fatty acids than other experimental groups (P < 0.0001). Besides, compared with other treatments, choline chloride supplementation caused a higher molar proportion of propionate (P < 0.001) while FR treatment resulted in a higher acetate production (P < 0.001) and acetate to propionate ratio (P < 0.01) compared to FR-RPC and FR-PMC treatments. Lambs born from FR-RPC ewes presented a greater average daily gain than those born from other ewes (P < 0.0001). Lambs reared by FR-PMC and FR ewes presented the highest and lowest weaning weight, respectively (P < 0.0001). It can be concluded that although feed restriction diminished animal production and offspring performance, simultaneous administration of propylene glycol, monensin sodium and rumen-protected choline chloride in restricted diets alleviated these negative effects and improved ewes milk production and offspring growth performance.