Effects of Forage Source and Method of Offering on Growth Performance, Starter Feed Intake, Rumen Fermentation, and Selected Blood Parameters in Preweaned Holstein Calves

This study evaluated the effects of forage source and method of offering on growth performance, starter feed intake, fecal score, rumen fermentation, and selected blood parameters in preweaned Holstein calves. Forty calves were assigned to four treatments (n = 10/group): straw offered separately from starter feed (A1), starter feed containing 7% straw (A2), alfalfa hay offered separately from starter feed (A3), or starter feed containing 7% chopped alfalfa hay (A4). Calves were monitored from birth to 60 days of age. On day 60, body weight was higher in A3 than in A1 (73.37 ± 7.87 vs. 65.82 ± 6.41 kg; p = 0.030). Average daily gain was higher in A3 than in A1 during days 15–30, higher in A3 and A4 than in A1 during days 30–45, and higher in A2 and A3 than in A1 during days 45–60 (p < 0.05). Starter feed intake differed during weeks 5–7, with higher values mainly observed in the straw-fed groups (p < 0.001). Fecal score was higher in A4 than in A2 in week 2 and higher in A4 than in A1 during weeks 3–6 (p < 0.05). Rumen pH on day 60 was higher in A4 than in A1 and A3 (p = 0.003), whereas volatile fatty acid concentrations did not differ among groups. Serum glucose on day 60 was higher in A3 than in A1 (p = 0.002), and total protein was lower in A1 than in A2, A3, and A4 on day 60 (p < 0.001). These findings suggest that forage source and method of offering may produce different biological responses in preweaned calves.