Influence of Pelleting Whole Cottonseed on Ration Digestibility and Milk Production and Composition

Two trials were conducted to determine the effect of pelleting whole cottonseed on milk production and composition and ration digestibility.In trial 1, four multiparous Holstein cows were paired by production and used in a 2 × 2 reversal design with 37-d experimental periods.Cow receiving pelleted cottonseed produced 35.12 kg/d milk and 31.74kg/d of 4% fat corrected milk as compared with 33.41 and 29.83 for cows receiving whole cottonseed.There were no significant differences in dry matter intake or milk composition between treatments.Yield of total solids and lactose was greater for cows receiving pelleted cottonseed as compared with whole cottonseed.Apparent digestibility coefficients for dry matter, gross energy, and crude protein were not different due to pelleting.In trial 2, four ruminal and abomasally cannulated Holstein steers were paired in a 2 x 2 reversal design and fed either pelleted on whole cottonseed for.10 d followed by a 7-d collection.Steers receiving the pelleted cottonseed had higher intakes of gross energy and crude protein.There were greater amounts of total crude protein and crude protein in the particulate phase of abomasal digesta from steers receiving pelleted cottonseed as compared with whole cottonseed.Apparent digestibility for crude protein for the whole tract was not different due to treatment.rations without sacrificing fiber.Smith et al. ( 19) fed WCS at 0, 5, 15, and 25% of the ration and found milk fat increased by .025%and milk protein and solids-not-fat decreased by .004%for each percent increase in WCS fed.An increase in milk production was observed by Anderson et al. (2) when 1.9 kg WCS was included in the ration of lactating dairy cows; however, other studies (3,12,19,20,21) have not observed any difference in milk production.Smith (19) summarized data indicating that WCS in maximally balanced rations will not necessarily increase feed or energy intake or milk production.The lint on WCS causes it to bridge in storage bins, making its use in mechanized feeding systems prohibitive.Pelleting WCS improves its handling characteristics; however, this ruptures the seed and releases the oil contained therein.Palmquist and Jenkins (15,16)reported that fatty acids, especially the unsaturated fatty acids, are highly toxic to the methanogenic and cellulolytic microorganisms in the rumen.Moody (12) observed depressed acid detergent fiber (ADF) digestibility when WCS was included in the ration at low fiber intakes; however, this depression was not observed with high fiber intakes.Rafalowski and Park (17) suggested that high fiber intakes may compensate for depressed digestibilities when fat is included in the ration.The objectives of these trials were 1) to determine the influence of pelleting WCS on milk production, composition, and ration digestibility and 2) to determine the influence of pelleting WCS on metabolism of protein in rumen.