Performance and digestibility in feedlot lambs fed hay based diets

ABSTRACT. This study aimed to evaluate the performance of feedlot lambs fed diets formulated with hay of different genotypes of Cynodon spp. and to compare the dry matter digestibility of diets using different evaluation methods (total fecal collection and chromium oxide). Suffolk crossbred neutered male lambs (n=30), with an average age of 90 days and average body weight of 21.5 kg ± 1.6. Diets were formulated using a standard concentrate and hay of the following genotypes of Cynodon dactylon: Jiggs, Vaquero, Tifton 68, Coast-Cross, Tifton 85 and Russell, in a 60:40 forage concentrate ratio, composing the treatments distributed in a randomized block design in a factorial 5 x 2 arrangement of 5 diets and 2 digestibility evaluation methods. Animals receiving Vaquero hay showed dry matter intake of 18.3; 16.9; 25.6; 20.7 and 24.2% higher than those fed hay of Jiggs, Tifton 68, Coast Cross, Tifton 85 and Russell, respectively. There was no difference between diets for digestibility using total fecal collection, chromium oxide and final weight of animals. Jiggs hay based diets allowed greater daily weight gain and better feed conversion.

摘要。本试验旨在评估饲喂不同基因型狗牙根属（Cynodon spp.）干草配制日粮的育肥羔羊生产性能，并对比不同评定方法（全收粪法（total fecal collection）与氧化铬指示剂法（chromium oxide））下的日粮干物质消化率（dry matter digestibility）。试验选用30只平均日龄90天、平均体重21.5kg±1.6kg的萨福克杂交去势公羔羊。试验日粮以标准精料与如下基因型的狗牙根（Cynodon dactylon）干草配制，饲粮粗精比为60:40，所用狗牙根基因型包括Jiggs、Vaquero、Tifton 68、Coast-Cross、Tifton 85及Russell。试验处理采用随机区组设计，设置5种日粮与2种消化率评定方法，构成5×2因子试验方案。饲喂Vaquero干草的羔羊，其干物质采食量（dry matter intake）分别较饲喂Jiggs、Tifton 68、Coast Cross、Tifton 85及Russell干草的羔羊高18.3%、16.9%、25.6%、20.7%与24.2%。采用全收粪法与氧化铬指示剂法评定的日粮干物质消化率，以及羔羊终末体重，在各组日粮间均无显著差异。以Jiggs干草为粗料来源的日粮，可使羔羊获得更高的日增重（daily weight gain）与更优的饲料转化率（feed conversion）。