Effects of neutral detergent fiber concentration of sugarcane-based diets on the performance of Holstein heifers

This study aimed to evaluate the effects of increasing the neutral detergent fibers (NDF) concentration of sugarcane-based diets on the growth and development of Holstein heifers. Twenty-seven Holstein heifers with a mean body weight of 265.5 ± 36.4 kg were housed in a sand bedded tie stall and fed individually. The experimental diet consisted of fresh sugarcane and concentrate. Three concentrations of sugarcane NDF were compared: 33% (SC33), 38% (SC38), and 42% (SC42). Crude protein content of experimental diets was 16%. The following parameters were evaluated: dry matter intake, weight gain and morphometric measures, digestibility, feeding behavior, and ruminal pH. The experimental design was a randomized block and all analyses were performed using the MIXED procedure in SAS. Intake of DM decreased as NDF concentration increased (p=0.07), but weight gain and growth were not significantly affected (p=0.74). As dietary NDF increased, chewing activity per unit DM intake increased (p=0.001), but rumen pH was not significantly affected (p=0.91). Diets formulated with 330?420 g of sugarcane NDF/kg of dry matter were sufficient to support the growth of Holstein heifers.

Evaluation of Two Procedures to Determine Acid and Neutral Detergent Fibers in Ruminant Feeds of the Temperate Region of Argentina

The objective of this work was to compare the traditional Van Soest's procedure to analyze neutral detergent fibers (NDF) and acid detergent fibers (ADF) using filtering crucibles (VS) with a semiautomatic method which uses filter bags in an ANKOM Technology Corp. instrument (ANK). Nine ruminant feeds widely used in the temperate region of Argentina were analyzed: soybean meal expeller, alfalfa, pasture silage, ryegrass, corn silage, weeping lovegrass, tall wheatgrass, guinea grass, and barley grass. Four runs were done for each technique and feed. The comparison of ADF and NDF means by the means test for paired samples showed no significant differences between techniques (α = 0.01). The variability among runs was greater with the VS method than the ANK, both for NDF, standard deviation (SD) = 0.71 vs 0.39, and for ADF, SD = 0.83 vs 0.56, but the differences were not significant. The linear regressions were VS = 1.43 + 0.95 ANK; R2 = 0.99, and VS = 0.53 + 0.98 ANK; R2 = 0.99 for NDF and ADF, respectively, which indicated a strong linear relationship among the results of both procedures. It was concluded that the ANK procedure gave results comparable to those of the VS method when ruminant feeds from the temperate region of Argentina were analyzed.

Evaluation of Alfalfa Weevil (Coleoptera: Curculionidae) Densities and Regrowth Characteristics of Alfalfa Grazed by Sheep in Winter and Spring

Fall regrowth of alfalfa, Medicago sativa (L.), serves as a major source of winter pasture for Montana sheep producers. In years of drought, alfalfa fields are extensively winter/spring grazed; however, the impact on crop health is unknown. Alfalfa paddocks were continuously grazed for 95 d in 2002 and 98 d in 2003 during winter and spring to determine the impact on spring and summer alfalfa regrowth, nutrient quality characteristics, and alfalfa weevil, Hypera postica Gyllenhal, densities. Grazed and non-grazed forage yield, crude protein (%), and acid and neutral detergent fibers (%) did not differ at harvest (P> 0.17) during either study year. Acid and neutral detergent fibers (kg/ha) were greater (P < 0.05) in non-grazed compared to grazed plots during 2002–2003. Alfalfa weevil densities were lower in grazed than non-grazed plots (P< 0.03) over four sampling dates during both study years. Winter/spring sheep grazing appears to offer potential for alfalfa weevil management without compromising yield or nutritive factors of subsequent alfalfa production.