Effects of hydrolyzed cottonseed protein supplementation on performance, blood metabolites, gastrointestinal development, and intestinal microbial colonization in neonatal calves

摘要

The objective of this study was to investigate theeffects of an enzymatically hydrolyzed cottonseed protein(HCSP) as a peptide source on performance, bloodmetabolites, gastrointestinal development, and intestinalmicrobes. Forty-eight newborn Holstein calves wererandomly assigned to 1 of the 4 dietary treatmentsincluding 0, 2, 4, and 6% of HCSP (dry matter basis).All calves received the same amount of pasteurizedwhole milk, weaned on d 56 of the experiment, andthe study was concluded on d 70. Data were analyzedusing PROC MIXED in SAS (SAS Institute Inc., Cary,NC) as a randomized complete block design with linearand quadratic contrasts. Results showed that increasedamount of HCSP linearly decreased the starter intakeduring the postweaning (d 57 to 70) and overall period(d 1 to 70). In addition, when dietary HCSP increasedduring the overall period, average daily gain tendedto linearly decrease. All skeletal growth variables alsolinearly decreased as dietary HCSP increased at theend of the study, except for body length, which didnot differ among the treatments. Serum cortisol concentrationwas higher in calves supplemented with 6%of HCSP at weaning and at the end of the study. Thisindicates that these calves may have experienced astressful condition compared with calves in other treatments.Total antioxidant capacity was quadraticallyaffected by HCSP supplementation; calves fed 2 and4% of HCSP diets had the highest total antioxidantcapacity, whereas calves fed 0 and 6% HCSP diets hadlower total antioxidant capacity at weaning and at endof the study. Calves supplemented with 6% HCSP hadlower empty reticulo-rumen and omasum weights andrumen wall thickness compared with calves in othertreatments at the end of the study. In conclusion, supplementationof HCSP at the rate of 2% of starter dietenhanced antioxidant status without any detrimentaleffects on the performance and metabolic status ofcalves, whereas greater inclusion rates impaired starterintake and growth of calves, and exposed them to astressful status.