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چکیده
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The current study evaluated the effect of corn grain processing method (ground corn: GC vs. steam flaked corn: SFC) with or without calcium salt of α-Linolenic acid (ALA) from flax oil on growth performance, ruminal fermentation parameters, and inflammatory markers in Holstein dairy calves. Forty-eight female dairy calves (averaging 3 d old and 40.1 kg body weight) in a completely randomized design as following treatments; 1) GC with no n-3 FA supplementation (GC-NALA), 2) GC with 30 g/kg n-3 FA source (GC-ALA), 3) SFC with no n-3 FA supplementation (SFC-NALA), and 4) SFC with 30 g/kg n-3 FA source (SFC-ALA). The calves were weaned on d 53 but the study finished 20 d after weaning (d 73 of experiment). Results showed that when calves received SFC with n-3 FA supplementation (SFC-ALA), average daily gain (ADG) improved at pre-weaning; (P = 0.04) and entire period (P = 0.05). Furthermore, calves fed SFC-ALA diet had greater (P = 0.05) blood glucose concentration at pre-weaning period and OM digestibility compared to other groups. The greater (P = 0.04) blood concentrations of tumor necrosis factor-alpha (TNF-α) and serum amyloid A (SAA; tendency; P = 0.07) at pre-weaning period were observed in calves received SFC-NALA diet than other experimental groups. Regarding the corn processing method, the ADG (post-weaning; P = 0.04), hip height (post-weaning; P = 0.04), ruminal concentration of total volatile fatty acids, and butyrate proportion (P = 0.04) increased, but ruminal acetate proportion (P = 0.02) reduced when calves received SFC compared to GC diets during pre-weaning period. Blood concentrations of TNF-α (P = 0.01) and SAA (P = 0.04) during pre-weaning period were lower in calves fed diets containing ALA than those fed diets without ALA. According to these results, supplemental n-3 FA improved growth performance when calves received SFC which could be related to reducing inflammatory responses.
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