Lane S F, Albrecht K A
Dept. of Meat and Anim. Sci., University of Wisconsin, Madison 53706.
J Anim Sci. 1991 Jan;69(1):305-17. doi: 10.2527/1991.691305x.
Two trials evaluated the potential for weaning lambs directly onto legume pasture at 28 d of age. Ewes and their twin-reared lambs were placed in paddocks on d 19; ewes were removed on d 28. In Trial 1, 60 lambs were allocated to three treatments: unweaned controls (CON1), lambs weaned onto first-cut alfalfa either without supplementary grain (WOG) or with up to 270 g.hd-1.d-1 supplementary grain (WG). Daily gains for the CON1, WOG and WG lambs were 309, 118 and 159 g for the period from d 28 to 40 (P greater than .05) and 241, 195 and 245 g for the period from d 40 to 56 (P greater than .05), respectively. In Trial 2, 80 lambs were allocated to four treatments: weaning onto first-cut alfalfa (early alfalfa, EA), second-cut alfalfa (late alfalfa, LA) birdsfoot trefoil (BFT) and unweaned controls (CON2, pastured on second-cut alfalfa). Daily gains for CON2 lambs were greater (P less than .05) than gains of EA and LA lambs (327 vs 136 and 136 g, respectively) for d 28 to 40, but not different (P greater than .05) for d 40 to 56 (245, 227 and 195 g, respectively). Gains for BFT lambs were lower (P less than .05) than for CON2 lambs for both periods (122 and 136 g, respectively), and BFT lambs appeared to be unthrifty after weaning. By d 32, weaning caused plasma glucose to decline 16.0 mg/dl and plasma nonesterified fatty acids to increase 365 mu eq/liter from preweaning levels. Hematocrit values ranged from 31 to 35% (Trial 1) and 25 to 29% (Trial 2), suggesting that the weaned lambs did not suffer from dehydration. Crossbred lambs can be weaned at 28 d of age directly onto first-cut or second-cut alfalfa.
两项试验评估了28日龄羔羊直接断奶后转至豆科牧草牧场的可能性。母羊及其双羔在第19天被放入围场；母羊在第28天被移出。在试验1中，60只羔羊被分配到三种处理方式：未断奶对照组（CON1）、断奶后转至头茬苜蓿且不补充谷物（WOG）或补充高达270 g·hd⁻¹·d⁻¹谷物（WG）的羔羊。从第28天至40天，CON1、WOG和WG组羔羊的日增重分别为309、118和159 g（P＞0.05）；从第40天至56天，日增重分别为241、195和245 g（P＞0.05）。在试验2中，80只羔羊被分配到四种处理方式：断奶后转至头茬苜蓿（早苜蓿，EA）、二茬苜蓿（晚苜蓿，LA）、百脉根（BFT）以及未断奶对照组（CON2，在二茬苜蓿牧场放牧）。在第28天至40天，CON2组羔羊的日增重高于EA和LA组羔羊（分别为327 g对136 g和136 g，P＜0.05），但在第40天至56天差异不显著（P＞0.05）（分别为245、227和195 g）。两个阶段BFT组羔羊的增重均低于CON2组羔羊（分别为122 g和136 g，P＜0.05），且BFT组羔羊断奶后显得生长不良。到第32天，断奶导致血浆葡萄糖从断奶前水平下降16.0 mg/dl，血浆非酯化脂肪酸增加365 μeq/升。血细胞比容值在31%至35%（试验1）和25%至29%（试验2）之间，表明断奶羔羊未出现脱水情况。杂交羔羊在28日龄时可直接断奶并转至头茬或二茬苜蓿牧场。
