چكيده انگليسي :
This study was conducted in two experiments investigating the effects of the interaction between corn grain processing and protein source on feed intake, growth performance, rumen fermentation, and blood metabolites of dairy calves. In the first experiment, Seventy-two 3-day-old calves were randomly assigned [36 male and 36 female per treatment to a 2 × 3 factorial arrangement] to one of six feed treatments: 1) coarse ground corn grain + 100% canola meal (CG-CAN), 2) coarse ground corn grain + 50% canola meal + 50% soybean meal (CG-CASY), 3) coarse ground corn grain + 100% soybean meal (CG-SOY), 4) steam-flaked corn grain + 100% canola meal (SF-CAN), 5) steam-flaked corn grain + 50% canola meal + 50% soybean meal (SF-CASY), and 6) steam-flaked corn grain + 100% soybean meal (SF-SOY). An interaction was found between the corn grain processing method and protein source for starter feed intake, total dry matter intake (TDMI), body weight (BW), average daily gain (ADG), and feed efficiency (FE). The greatest feed intake and DMI were observed in the CG-CAN (post-weaning) and SF-SOY (total period) treatments, but in the pre-weaning period, feed intake was greater when calves received CG-CAN than in the other treatments. BW, ADG, and FE were higher in calves receiving SF-SOY and CG-CAN than in the other treatments. Body length, withers height, heart girth, hip width, and hip height were not affected by the corn grain processing method and interaction. No interaction between the corn grain processing method and protein source was observed for blood glucose, TG, BUN, pH, and rumen fermentation profile. For BHB concentration, a 2-way interaction was observed between corn grain processing method and time, indicating that BHB concentration was positively affected in coarsely ground corn compared to steam-flaked corn during pre- and post-weaning periods. Results indicate that rumen pH, acetate and propionate molar proportions, and total VFA concentration did not differ between treatments. Overall, the study suggests that a combination of SF corn and soybean protein may be optimal for maximizing calf performance. This underscores the importance of considering the interaction between corn grain processing method and protein source in calf nutrition. The second experiment was performed with forty-eight 3-day-old Holstein calves (24 females and 24 males) with starting BW of 40 ± 0.5 kg were randomly assigned [24 males and 24 females per treatment in a 2 × 2 factorial arrangement] to 1 of 4 treatments: 1) CRC-LR, (cracked corn + canola meal + 6% extrude), 2) CRC- HR, (cracked corn + canola meal + 12% extrude), 3) SFC-LR (steam flaked corn + canola meal + 6% extrude) and 4) SFC-HR (steam flaked corn+ + canola meal + 12% extrude). All starters had the same energy, protein and other nutrient composition, but differed in their physical form of corn and rumen undegradable protein levels. BW and ADG were higher in calves fed on CRC-HR and SFC-LR treatments that showing the interaction between corn processing method and RUP level in pre- and post-weaning. Feed efficiency was improved in pre-weaning in calves fed on CRC-HR and SFC-LR diet. The CRC-HR and SFC-LR diets improved Body length, Wither height, Heart girth and Hip height. Ruminal pH was greater when calves received CRC treatment in comparison with SFC treatment in the pre-weaning and post-weaning period. The higher ruminal valerate concentration was founded in calves fed SFC in pre- and post-weaning whereas, calves fed CRC-LR and SFC-HR diet, increased ruminal isovalerate concentration. glucose, TG, BUN and BHBA concentration did not influence with RUP level, but, BUN concentration was greater when calves fed CRC-LR treatment. Results indicate that CRC-HR and SFC-LR treatments improves performance dairy calves, rather than other two treatments.
