Interaction between particle size and source of forage on performance, ruminal and skeletal growth parameters of Holstein dairy calves

The present study was conducted to evaluate the interactions between forage source (alfalfa hay vs. wheat straw) and particle size (fine vs. large) on growth performance, starter intake and ruminal fermentation of Holstein dairy calves. For this purpose, 48 Holstein dairy calves in a completely randomized block design (6 males and 6 females for each treatment) with 2 × 2 factorial arrangements were allocated to experimental diets including: 1) alfalfa hay with fine particle size, 2) alfalfa hay with long particle size, 3) wheat straw with fine particle size, and 4) wheat straw with long particle size. Calves entered the trial on d 4 and the trial lasted on d 70 of the age. Results showed that there was no interaction between forage source and particle size on growth performance, starter intake and feed efficiency of Holstein dairy calves during the all three periods. Skeletal growth characteristics were not affected by experimental diets. Results indicate that ruminal pH, total volatile fatty acids, acetate, propionate, butyrate and valerate molar proportions were similar across treatments. In general, our findings indicate that the different source and particle size of forage had similar effects on performance, skeletal growth and ruminal fermentation in the Holstein dairy calves.