Effect of maceration of bromegrass-alfalfa silage on ruminal degradability and performance of lactating dairy cows

Abstract

. 2006. Effect of maceration of bromegrass-alfalfa silage on ruminal degradability and performance of lactating dairy cows. Can. J. Anim. Sci. 86: 311-315. Maceration of bromegrass-alfalfa sward increased effective ruminal degradability of dry matter, neutral detergent fibre, and gross energy, but decreased the degradability of protein.Despite improvement in ruminal degradation kinetics, inclusion of the macerated silage (43% of total mixed ration dry matter) between weeks 7 and 15 of lactation had limited effect on lactational performance.Key words: Forage, silage, maceration, rumen degradability, lactation Ouellet, D. R., Lapierre, H. et Chiquette J. 2006. Effet de la macération d'un mélange d'ensilage brome-luzerne sur la dégrad-abilité ruminale et les performances des vaches laitières. Can. J. Anim. Sci. 86: 311-315. La macération d'un mélange bromeluzerne a augmenté la dégradabilité ruminale effective de la matière sèche, de la fibre détergente neutre et de l'énergie brute mais diminué la dégradabilité de la protéine. Malgré une amélioration de la cinétique de la dégradation ruminale, l'inclusion de l'ensilage macéré (43% de la matière sèche de la ration totale mélangée) entre les semaines 7 et 15 de lactation a eu un effet limité sur les performances des vaches laitières. Mots clés: Fourrage, ensilage, macération, dégradabilité ruminale, lactationOver the past decades, intensive mechanical conditioning, referred to as maceration, has been developed to improve forage conservation. Indeed, maceration has been shown not only to increase the field drying rate (Savoie et al. 1993), but also to improve the ensiling process of forages (Hintz et al. 1999). Other than those in which corn silage was used, few studies have been conducted that examine the effects of maceration of forage on ruminal degradability and animal performance. Broderick et al. (1999) reported a greater milk yield in two of four experiments when 61% of the dietary dry matter (DM) was provided by macerated vs. longchopped alfalfa silage. In contrast, there was no beneficial effect on milk production when cows were fed a diet containing 41% of the dietary DM provided by macerated ryegrass silage (Broderick et al. 2002).The objectives of this study were to determine the effects of the maceration of a mixed sward of bromegrass-alfalfa on rumen degradability of silage, total tract apparent digestibility, and lactational performances of dairy cows.Two fields containing 60% bromegrass and 40% alfalfa were harvested on 3 consecutive days with (1) a prototype pull-type forage harvester (model 1218, Dion Machineries, Quebec) modified to include two corrugated rolls (Roberge et al. 1998) to produce macerated silage (MS) or (2) a conventional forage harvester (New Holland, model 900) to produce unmacerated silage (US). Both harvesters were operated simultaneously and equally distributed between the two fields. Particle size distribution, evaluated using standard method S424.1 (American Society of Agricultural Engineers 1999), indicated a geometric mean len...