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Dimorphic chronological development of ruminant digestive system supports development of equivalent muscle fatty acid profiles in continuously suckled and weaned Katahdin lambs
Dimorphic chronological changes in gastrointestinal tract morphometry and muscle fatty acids profile, in Fall born Katahdin lambs reared in two different rearing systems (continuously suckled = CS and weaned = W) were characterized. The lambs were randomly allocated to be weaned (W, n = 31) at 2.5 months of age or continuously suckled (CS, n =32). Lambs (CS and W) were creep fed ad lib, then weaned or continuously suckled while accessing orchard grass hay and finisher feed ad lib until the end of the study. Four 2.5 months old wether lambs (PW) and eight 4 months old wether lambs (CS = 4 and W = 4) were euthanized. Harvested gastrointestinal tracts (GIT) gross morphometries and longissimus dorsi muscle fatty acid profiles of lambs were determined. Age effects (CS, W vs PW; P < 0.05) but not rearing system effects on GIT weight (2221.88, 2104.95, vs 1320.75g), rumen weight (559.70, 571.48, vs 262.95 g), rumen weight as a percentage of total GIT weight (25.16, 27.25 vs 20.13 %), fore-stomach weight (727.60, 745.00 vs 343.90g), fore-stomach weight as a percentage of the entire GIT weight (32.75, 35.53 vs 26.04%) and cecum weights (118.53, 122.88 vs 65.50g) were determined for CS, W and PW lambs, respectively. Age effects (CS, W vs PW; P < 0.05) on abomasum weights (163.33, 146.68 vs 77.55g), abomasum weight as a percentage of the entire GIT weights (7.23, 6.95 vs 5.85%), small intestine weights (1006.23, 867.20, vs 691.28g), small intestine weight as a percentage of entire GIT weight (45.09, 41.07 vs 51.98%) and small intestine lengths (1077.50, 943.00 vs 783.25 cm) were also determined, but notably presented a different numerical trend for subsections of the GIT harvested from CS and W lambs. Collectively, these descriptive statistics indicates dimorphic development of CS and W lambs’ GIT to support relatively greater enzymatic intestinal versus ruminal fermentative digestion, in CS than in W lambs. Furthermore, pancreas weights (66.73 and 54.95) were significantly different (P< 0.05) between CS and W lambs, respectively. However, once again age (P< 0.05) but not rearing system affected total fatty acids (13.25, 12.11 vs 10.44 g/100g), SFA (5.61, 4.87 vs 4.30 g/100g), and UFA (7.64, & 7.24 vs 6.14 g/100g) in CS, W vs PW lambs muscles. Conclusively, dimorphic chronological development of ruminant digestive system supports development of equivalent muscle fatty acid profiles in continuously suckled and weaned Katahdin lambs.
Keywords: Gastrointestinal tract development