The aim of the present study was to evaluate the genetic correlations among real-time ultrasound carcass, BW, and scrotal circumference (SC) traits in Nelore cattle. Carcass traits, measured by real-time ultrasound of the live animal, were recorded from 2002 to 2004 on 10 farms across 6 Brazilian states on 2,590 males and females ranging in age from 450 to 599 d. Ultrasound records of LM area (LMA) and backfat thickness (BF) were obtained from cross-sectional images between the 12th and 13th ribs, and rump fat thickness (RF) was measured between the hook and pin bones over the junction between gluteus medius and biceps femoris muscles. Also, BW (n = 22,778) and SC (n = 5,695) were recorded on animals born between 1998 and 2003. The BW traits were 120, 210, 365, 450, and 550-d standardized BW (W120, W210, W365, W450, and W550), plus BW (WS) and hip height (HH) on the ultrasound scanning date. The SC traits were 365-, 450-, and 550-d standardized SC (SC365, SC450, and SC550). For the BW and SC traits, the database used was from the Nelore Breeding Program-Nelore Brazil. The genetic parameters were estimated with multivariate animal models and REML. Estimated genetic correlations between LMA and other traits were 0.06 (BF), -0.04 (RF), 0.05 (HH), 0.58 (WS), 0.53 (W120), 0.62 (W210), 0.67 (W365), 0.64 (W450 and W550), 0.28 (SC365), 0.24 (SC450), and 0.00 (SC550). Estimated genetic correlations between BF and with other traits were 0.74 (RF), -0.32 (HH), 0.19 (WS), -0.03 (W120), -0.10 (W210), 0.04 (W365), 0.01 (W450), 0.06 (W550), 0.17 (SC365 and SC450), and -0.19 (SC550). Estimated genetic correlations between RF and other traits were -0.41 (HH), -0.09 (WS), -0.13 (W120), -0.09 (W210), -0.01 (W365), 0.02 (W450), 0.03 (W550), 0.05 (SC365), 0.11 (SC450), and -0.18 (SC550). These estimates indicate that selection for carcass traits measured by real-time ultrasound should not cause antagonism in the genetic improvement of SC and BW traits. Also, selection to increase HH might decrease subcutaneous fat as correlated response. Therefore, to obtain animals suited to specific tropical production systems, carcass, BW, and SC traits should be considered in selection programs.

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This study aimed to characterise progeny of sires representing major families in the Poll Nellore breed. Fourteen Poll Nellore sires, two Angus sires and one Brahman sire were mated by AI to~400 multiparous Poll Nellore dams. Calves were raised and stocked on pasture in central Brazil until reaching~18 months of age, then fed a sugarcane bagasse-based diet on an ad libitum basis until reaching market weight and finish (average 23 months). There were 236 Poll Nellore (N), 38 Angus · Poll Nellore (AN) and 31 Brahman · Poll Nellore (BN) calves born in total. The weaning and 423-day weight weights, and growth rates and pre-and post-weaning were greater (P < 0.05) in males than in female calves, and were influenced by breed and by sire within the N animals. The weaning weights were higher (P < 0.05) in AN and BN than in N calves. The 423-day weight weights were greater (P < 0.05) in AN calves, followed by BN, with straightbred N being lightest. Feedlot average daily gain was unaffected (P > 0.05) by sex or by sire within N, but was lowest (P < 0.05) in N cattle, and highest in AN and BN animals, which did not differ (P > 0.05). Heifers reached the end of the study with lower bodyweight (BW) and dressing percentage than steers, resulting in lower carcass weights, smaller longissimus muscle areas (LMA), but greater 12th to 13th rib backfat (BF) and similar marbling score and mean shear force. However, the proportion of carcasses grading Choice or Prime was numerically greater in heifers than in steers (23.6% vs 9.8%). AN cattle reached greater harvest weights than BN, and those were heavier than N cattle (P < 0.001). However, dressing percentages were lowest in AN animals, so that there was no significant difference in carcass weight between AN and BN cattle. AN carcasses also had greater LMA, BF and marbling scores than the N carcasses. The proportion of carcasses grading Choice or Prime was numerically greater in AN cattle than in the BN and N groups (25.9%, 11.8% and 15.9%, respectively). Steaks from AN calves were more tender than N steaks, with the BN steaks being intermediate. There was significant variation among N sires for final BW, dressing percentage, carcass weight, LMA and marbling score, but not for BF or mean shear force. The percentages of carcasses of N cattle grading Choice or Prime ranged from 0% to 61.5%. Three N sires produced progeny with greater than 40% of carcasses grading Choice or above (Berílio OB, Furador OB, and Litoral OB). Likewise, three N sires (Blitz OB, Furador OB and Sossego OB) had progeny with 67%, 62% and 75%, respectively, of steaks classified as tender. This study confirmed that Zebu cattle have inferior carcass and meat quality relative to AN crossbreds under tropical conditions, however there is substantial variation within the N breed for these traits, and several sires have a proportion of their progeny comparable in terms of meat tenderness to those of Angus sires.

In order to test the performance of bacterial cellulose/polycaprolactone composite (BC/PCL) and pure bacterial cellulose (BC) as tissue substitutes in rabbits' cornea, a superficial ulcer containing 5mm in diameter and 0.2mm deep was made in the right cornea of 36 rabbits, then a interlayer pocket was created from the basis of this ulcer. Twelve rabbits received BC/PCL membrane and 12 were treated with BC membranes, both membranes with 8mm in diameter. The remaining rabbits received no membrane constituting the control group. The animals were clinically followed up for 45 days. Three animals of each group were euthanized at three, seven, 21, and 45 days after implantation for histological examination of the cornea along with the implant. Clinical observation revealed signs of moderate inflammatory process, decreasing from day 20th in the implanted groups. Histology showed absence of epithelium on the membranes, fibroplasia close to the implants, lymph inflammatory infiltrate with giant cells, collagen disorganization, with a predominance of immature collagen fibers in both groups with implants. Although inflammatory response is acceptable, the membranes used does not satisfactorily played the role of tissue substitute for the cornea during the study period.

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