PHYSICAL EFFECTIVENESS OF THE NEUTRAL DETERGENT FIBER OF WHOLE LINTEDCOTTONSEED RELATIVE TO THAT OF ALFALFA SILAGE AT 2 LENGTHS OF CUT

The effectiveness of the neutral detergent fiber (NDF) of whole linted cottonseed to stimulate chewing was examined relative to the effectiv eness of the NDF of alfalfa silage at two lengths of cut. Twelve Holst ein cows (125 d of lactation) were fed diets containing alfalfa silage s differing in theoretical length of cut, with or without cottonseed s ubstituted far alfalfa silage at 27% of alfalfa NDF. The experiment wa s a replicated (n = 3) 4 x 4 Latin square design with a 2 x 2 factoria l arrangement of treatments. Length of cut had no effect on milk produ ction or composition, and substitution of cottonseed increased milk pr oduction but did not affect milk composition. An interaction was obser ved between treatment effects for dry matter intake, total chews per d ay, and total chewing time (minutes per day). Physical effectiveness o f cottonseed NDF was calculated by dividing the total chewing time per unit of cottonseed NDF by total chewing time per unit of alfalfa sila ge NDF. Physical effectiveness of cottonseed NDF was calculated to be 50% of long-cut and 127% of short-cut alfalfa silage NDF. The interact ion observed between main effects for total chewing time per day indic ated that the physical effectiveness of whole linted cottonseed was re lative and depended on the characteristics of the forage that it repla ced.