Impact of weaning age on rumen development in artificially reared lambs1

Abstract

This study examined the impact of weaning age (4 vs. 6 wk) on rumen morphological and metabolic development in artificially reared lambs. Thirty-two mixed-sex lambs (2 to 5 d old) were randomly allocated to 1 of 2 weaning groups: early weaning (EW; 4 wk) and control (Ctrl; 6 wk). Lambs were individually penned and fed milk replacer (MR; 24% CP and 25% fat, DM basis) at 20% of their corresponding initial BW. Weaning was achieved by gradual reduction of MR allowance over a period of 3 wk using a step-down procedure. Concentrate and meadow hay were offered ad libitum from 1 d of the study until 6 wk, when lambs were transferred to a mixed sward pasture. At week 4, individual DMI were recorded and blood samples collected to measure β-hydroxybutyrate (BHBA) and NEFA. Eight animals per group were euthanized at week 4 and 16 to evaluate short chain fatty acids (SCFA) and histomorphometry of the rumen walls: dorsal (DS), ventral (VS), dorsal blind (DBS), and ventral blind (VBS) sacs. Linear mixed models were used to analyze the effect of weaning treatments at week 4 and 16, and to compare between timepoints and between rumen sites. Dry matter intake and rumen SCFA profiles were similar between groups (P > 0.10) at week 4 and 16. Plasma concentrations of BHBA were greater (P = 0.03) in EW than in Ctrl lambs, while NEFA did not differ (P > 0.10) between groups at week 4. No effect of weaning age on rumen empty weight, and papillae density, length, width, surface area ratio, and muscle layer thickness at any of the 4 rumen sites was found (P > 0.10) at either week 4 or week 16, except for greater (P = 0.02) papillae epithelium thickness in the DBS at week 4 in EW than Ctrl lambs. Papillae morphology and muscular thickness differed across rumen sites at week 4 and week 16 (P < 0.05), except for papillae density and surface area ratio at 4 week (P > 0.10). Rumen papillae length, width, and muscle layer thickness increased while papillae density and surface area ratio decreased (P < 0.05) between 4 and 16 wk. The results of this study indicate that morphological and physiological development of the rumen can be accelerated to support weaning of artificially reared lambs at 4 wk, using a step-down weaning system. Morphological differences between rumen sacs denote that future studies in lambs evaluating the impact of different diets should involve representative sampling across the rumen rather than a single site to more accurately study rumen development and ontogenic changes.

Effect of Divergent Feeding Regimes During Early Life on the Rumen Microbiota in Calves

“…In post-weaned calves, the consumption of solid diets is associated with a progressive shift in ruminal microbial composition toward a more diverse microbiota ( Rey et al, 2014 ; Dias et al, 2017 ; Dill-McFarland et al, 2017 ). The ruminal microbiota in young ruminants acquires an adult-like composition as the solid feed intake increases between the weaning transition and 1 year of age ( Dill-McFarland et al, 2019 ), with recent studies indicating that an increased solid feed intake can result in adult-like fermentation profiles ( Cristobal-Carballo et al, 2019 ). As a result, dietary interventions, aimed at altering ruminal microbial composition and fermentation profiles, may be most effective during the weaning transition of young ruminants.…”

Dietary supplementation of yeast cell wall improves the gastrointestinal development of weaned calves

“…Rumen is an important organ of ruminants for nutrient digestion and absorption. The healthy development of rumen at young age is closely related to production performance in the future ( Cristobal-Carballo et al., 2019 ). The present study did not find a statistical difference in stomach weight between CON and YCW groups.…”

Effects Study of Early Weaning Time on the Growth and Development of Dairy Sheep Lamb

“…Postmortem, some of rumen, duodenum, jejunum and ileum was collected, emptied, washed with tap water and dried with paper towels. Histology slices were prepared followed by Carballo et al [13]. Briefly, Three to five segments (approximately 5 × 15 mm with 5 mm separation between each selected segment) were trimmed.…”