Effect of preweaning nutritional management on yearling weight response in an open-herd selection program.

Records on 276 progeny were collected in the final 2 yr (1984 and 1985) of an 8-yr Hereford cattle selection project. Selection was practiced using the top sires from the American Hereford Association's National Cattle Evaluation based on yearling weight expected progeny difference. An unselected control line was maintained to monitor environmental change. One-half of each line was creep-fed during the preweaning period for the last 2 yr to evaluate genotype x environment interactions. Direct response to yearling weight selection averaged 28 +/- 8 kg. Correlated response to selection amounted to .057 +/- .028 kg/d in preweaning ADG, 14 +/- 6 kg in weaning weight, .085 +/- .033 kg/d in postweaning ADG, 4.6 +/- 1.5 cm in yearling hip height and 11.2 +/- 3.0 cm2 in yearling pelvic area. Yearling fat thickness and scrotal circumference were not significantly affected by selection. Significant effects of creep feeding were observed for yearling weight (15 +/- 3 kg), preweaning ADG (.067 +/- .012 kg/d), weaning weight (13 +/- 2 kg), yearling hip height (1.2 +/- .5 cm) and yearling fat thickness (.07 +/- .03 cm). Postweaning ADG, yearling pelvic area and yearling scrotal circumference were not affected by creep feeding. No significant genetic group x creep feeding effects were found for any of the traits analyzed, indicating calves genetically superior for growth did not gain any additional advantage from creep feeding.

Genetic parameter estimates for growth and fleece characteristics in Targhee sheep.

Weaning weights at 60 (WW60) and 120 d (WW120), 60- to 120-d postweaning gains (PWG) for lambs weaned at 60 d, 120- to 365-d postweaning gains (YG) for lambs weaned at 120 d, fleece weights (FWT), and fiber diameters (FD) from 20 Targhee flocks were used to estimate parameters required for multiple-trait genetic evaluation. Flocks from western states (n = 10) recorded primarily WW60 (n = 1,762), WW120 (n = 5,961), YG (n = 2,388), FWT (n = 2,824), and FD (n = 2,000). Eastern flocks primarily recorded WW60 (n = 1,754) and PWG (n = 1,237). Heritability estimates were .01 for WW60 (.00 for western flocks and .07 for eastern flocks), .10 for WW120, .33 for PWG, .20 for YG, .41 for FWT, and .58 for FD. Additive maternal and maternal permanent environmental effects as a proportion of phenotypic variance were .10 and .09, respectively, for WW60 and .05 and .08 for WW120. In western flocks, maternal additive and permanent environmental effects on WW60 and WW120 were highly correlated (> .81), whereas WW120 and YG had a small positive additive genetic correlation (.19) but a negative residual correlation (-.34). Fleece weight had a genetic correlation of .50 with WW120 and YG. Supplemental analyses suggested that the observed genetic relationship between fleece weight and weaning weight arose primarily from a genetic association between additive direct genetic effects on fleece weight and additive maternal effects on weaning weight. Fiber diameter was nearly independent of body weights but had an undesirable additive correlation of .51 with FWT. In eastern flocks, WW60 and PWG had an additive correlation of .71 and a residual correlation of .15.

Prediction of carcass characteristics by real-time ultrasound in barrows and gilts slaughtered at three weights.

The carcass characteristics of 27 market barrows and 27 market gilts were evaluated at various times (n = 8) with real-time ultrasound (Aloka 210 DX) from approximately 20 kg until slaughter at three end points. The pigs were randomly assigned to slaughter weight groups of 91, 104.5, and 118 kg at weaning time. Correlations were determined over slaughter weight group and sex, and the accuracies of ultrasound measurements were also evaluated. The regressions of ultrasound 10th-rib fat and ultrasound longissimus muscle area on live weight were also developed. Correlations between actual and ultrasound-measured last-rib fat, 10th-rib fat, and longissimus muscle area were high (r = .91, .63, and .53, respectively; P less than .01). The accuracy of ultrasound longissimus muscle area prediction was lower for 118-kg pigs than for the two lighter groups, whereas the accuracy for prediction of last-rib fat was lower for 91-kg pigs than for the two heavier groups, as indicated by higher absolute differences (P less than .05). Last-rib fat and longissimus muscle area tended to be overestimated and 10th-rib fat tended to be underestimated by real-time ultrasound. Prediction of last-rib fat by ultrasound was more accurate for gilts than for barrows, as indicated by a lower absolute difference (P less than .05).

Growth and development of bovine fetuses and neonates representing three genotypes.

Growth was examined in bovine fetuses and neonates that typically differ in mature size and postnatal developmental pattern. Pregnancies were established from matings expected to produce early (E), late (L), and intermediate (I) maturing postnatal growth patterns. Tissues were collected at 100 and 200 d of gestation and 30 d postnatal. Muscle:body weight ratios were lower at 100 and 200 d for the E maturity type than for the L maturity type (P < .05). This differs from observations of muscle:body weight ratios made at 30 d postnatal, at which time ratios for E were either greater than (triceps brachii, P < .05) or similar to those for L. Few differences due to maturity type were observed at 100 d for bone weight:body weight ratios; however, at 200 d of gestation E bone weight:body weight ratios were generally lower (P < .05) than those for L. The genotypic relationship for bone weight:body weight ratio at 30 d postnatal was similar to that observed at 200 d of gestation. Observations of organ weight:body weight ratios revealed no clear patterns due to maturity type. The genotypic relationship for total muscle DNA content was similar to that observed for muscle weight. These results indicate that fetal muscle development differs in cattle that have different postnatal growth patterns by as early as 100 d of gestation and that differences in fetal muscle growth are related to differences in muscle hyperplasia.

Tracheal osteochondroma in a dog.

A young female Labrador Retriever-type dog had a 4 1/2-month history of respiratory distress, which eventually became severe, leading to cyanosis. Physical examination suggested an upper airway obstructive lesion, which was confirmed by bronchoscopy and radiography to be a mass in the thoracic portion of the trachea. The mass was removed surgically and, on histologic examination, was found to be an osteochondroma. Six months after surgical extirpation, there was no indication of recurrence of tumor.