Growth and feed conversion efficiency of Dorper and Rambouillet lambs.

Data from Dorper and Rambouillet ram lambs (n = 79) were used to estimate breed means for postweaning growth rate, feed intake, feed conversion efficiency (kilograms of gain divided by kilograms of feed consumed), and residual feed intake on a high concentrate diet during the typical age and weight range for U.S. lamb production. Lambs were progeny of 6 unrelated sires/breed and were born over a 2-yr period. Dams of the lambs were a representative sample of Dorper ewes in the United States and Rambouillet ewes in Texas. Data were analyzed using SAS PROC MIXED with a model that included year, breed, birth type, and feeder pen as fixed effects and sire as a random effect. The mean BW at the start of the feeding trial was 31.4 ± 3.7 kg at a mean age of 92.7 ± 9.2 d. Electronic feeders were used to record individual animal feed intake. Growth rate and feed intake were measured for 77 d during the postweaning growth period. Mean ADG was 340 ± 9.2 g for Dorper lambs and 346 ± 8.6 g for Rambouillet lambs. The mean final bodyweight was 58.1 ± 4.8 kg when the mean age was 170 d. Average daily feed intake was 2,223 ± 50 g for Dorper lambs and 2,215 ± 48 g for Rambouillet lambs. Feed conversion efficiency was 0.153 ± 0.003 for Dorper lambs and 0.158 ± 0.003 for Rambouillet lambs. No significant differences were observed between Dorper and Rambouillet lambs for weaning weight, postweaning gain, final weight, feed intake, feed conversion efficiency, or residual feed intake. Growth rate, feed intake, and feed conversion efficiency were similar for Dorper and Rambouillet ram lambs fed from a mean of 31 kg BW and 93 d of age to a mean BW of 58 kg and a mean age of 170 d.

Heritability of juniper consumption in goats.

Data from goats (n = 505), collected over a 4-yr period, were used to estimate the heritability of juniper consumption. Juniper consumption was determined by near-infrared spectroscopy on fecal samples (n = 1,080) collected from female Boer-cross goats grazing pastures with a variety of plants, including juniper. The animals with records were progeny of 72 sires. Individual goats had from 1 to 4 observations over a 4-yr period. Predicted juniper consumption for individual observations ranged from -5 to +62% of the diet. Data were analyzed with a mixed model that included management group as a fixed effect, BW as a covariate, and permanent environment, animal, and residual as random effects. Management group was a significant source of variation. Least squares means of juniper consumption, as a percentage of the total intake, for management groups varied from 19 to 47%. Heritability of juniper consumption was 13%. Repeatability of juniper consumption was 31%. These results suggest that progress to selection for goats that will consume greater amounts of juniper is obtainable, but is expected to be slow.

Length of docked tail and the incidence of rectal prolapse in lambs.

A multistate cooperative study was conducted to study the current issue of tail length in docked lambs and its relationship to incidence of rectal prolapse. A total of 1,227 lambs at six locations were randomly allocated to two or three tail dock treatments: 1) short--tail was removed as close to the body as possible, 2) medium--tail was removed at a location midway between the attachment of the tail to the body and the attachment of the caudal folds to the tail, and 3) long--tail was removed at the attachment of the caudal folds to the tail. Short-docked lambs had a greater (P < 0.05) incidence of rectal prolapse (7.8%) than lambs with a medium (4.0%) or a long (1.8%) dock. Female lambs had a higher (P < 0.05) incidence of rectal prolapse than male lambs. At two stations, lambs were finished either in a feedlot on a high-concentrate diet or on pasture with no grain supplementation. At one station, with a very low incidence of rectal prolapse, there was no difference in incidence between lambs finished in the feedlot or on pasture; however, at the station with a relatively high incidence of rectal prolapse, lambs in the feedlot had a higher (P < 0.05) incidence than lambs on pasture. The half-sib estimate of heritability for the incidence of rectal prolapse was low (0.14). The results of this study strongly implicate short dock length as a cause of rectal prolapse in lambs finished on high-concentrate diets. Furthermore, the results of this study and the only other study known conducted on this issue strongly suggest that docking lambs at the site of the attachment of the caudal folds to the tail will result in a negligible incidence of rectal prolapse.