MEAT SCIENCE

The aims of the study were to investigate the effects of immunization against GnRH using OL protein (Ovalbumin-LHRH-7) on feedlot performance, carcass, meat quality and some reproductive traits in Kivircik ram lambs. Ram lambs in the immunization (I, n = 7) group were immunized against GnRH using OL protein and boosted 2 weeks later. Control (C, n = 7) group was not treated. The animals were kept at pasture for 6 weeks after the first immunization, subjected to a 70 day fattening program, and then slaughtered. Growth performance, various carcass and meat quality characteristics were not affected from the immunization. GnRH immunization induced GnRH antibody production, suppressed testosterone production and testicular growth (P<0.01). Testicular structure was negatively affected from the immunization, but not pituitary. These results suggest that immunization against GnRH with OL could be an alternative castration technique in ram lambs without negatively affecting carcass and meat quality characteristics. (C) 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved

TROPICAL ANIMAL HEALTH AND PRODUCTION

The objective of this study was to determine the fattening performance and carcass and meat quality characteristics of Kivircik twin male lambs. Twelve lambs at approximately 5 months of age were subjected to a finishing diet for 60 days. Average live weight of lambs at the beginning and the end of the fattening were 23.14 +/- 0.84 and 39.0 +/- 1.01 kg, respectively. Daily live weight gain and feed conversion efficiency were found as 0.265 +/- 0.007 and 6.14 kg, respectively. Hot carcass weight, cold carcass weight, and dressing percentage were 19.6 +/- 0.6 and 18.9 +/- 0.6 kg and 48.1 +/- 0.3%, respectively. Kidney-pelvic fat weight, internal fat weight, and m. longissimus dorsi area were 0.117 +/- 0.023 and 0.364 +/- 0.041 kg and 15.26 +/- 0.70 cm(2), respectively. The percentages of leg, back loin, forearm, shoulder, neck, flank-chest, kidney-pelvic fat, and internal fat in carcasses of the lambs were found as 34.1 +/- 0.4%, 19.6 +/- 0.3%, 21.0 +/- 0.2%, 7.0 +/- 0.3%, 10.5 +/- 0.3%, 7.2 +/- 0.2%, 1.3 +/- 0.1%, and 1.8 +/- 0.1%, respectively. Averages water content, ash, protein content, and fat content of meat samples were 73.4%, 1.0%, 19.5% and 3.6%, respectively. pH and thiobarbituric acid reactive substances values of meat samples were 5.55 and 0.056 +/- 0.017. L*(lightness), a*(redness), and b*(yellowness) values were recorded as 43.87, 12.69, and 10.22, respectively. Thus, we conclude that fattening performance, carcass, and meat quality of Kivircik lambs are satisfactory levels than that of other native breeds

The effects of docking on performance and carcass characteristics of male Karaka lambs

The effects of tail docking at birth on growth performance and carcass characteristics of fat-tailed male Karakas lambs were investigated. A total of 23 Karakas single-born male lambs was used in this study. Nine were docked at one day of age using rubber elastrator rings and the rest was left intact. After weaning, the lambs were fed a finishing diet for 70 days, and then slaughtered to evaluate carcass characteristics. Total weight gains during the finishing period were 14.3 + 1.00 and 18.9 + 0.82 kg and average daily live weight gains 204.7 + 14.41 and 269.9 + 11.72 g for the undocked vs. the docked group, respectively. The carcasses of the docked group contained more kidney, pelvic and internal fat than the intact lambs as well as a higher percentage of subcutaneous and intramuscular fat. The weights of the different carcass cuts of the docked lambs were also heavier that those of the intact group. The results indicated that the tail docking of fat-tailed Karakas lambs at birth improved weight gain and desirable carcass characteristics compared to those of undocked lambs. Keywords: Karakas lambs, Fat tail docking, Growth performances, Slaughter South African Journal of Animal Science Vol.33(3) 2003: 185-19

Evaluation of immunocastration conjugates based on GnRH linked to carrier molecules in a male rodent model

Gonadotropin-releasing hormone (GnRH) stimulates the pituitary gland to secrete sex hormones. In the present study, we evaluated different conjugates of GnRH to abrogate sex hormone secretion in a male rat model. Firstly, GnRH-I was conjugated to keyhole limpet haemocyanin (KLH) using either whole-sequence GnRH-I or an analogue of GnRH-I (CHWSYGLRPG-NH2) using glutaraldehyde cross linkage. Six-week-old Sprague-Dawley male rats (n=6) were immunized intramuscularly with the conjugates adsorbed onto alum, equivalent to 50 μg of GnRH peptide and administered in weeks 1, 3, 5 and 7. The study was concluded in week 15. Comparison was made with untreated controls and previously established anti-fertility conjugates: CHWSYGLRPG-NH2 (GnRH-I) or CHWSHDWKPG-NH2 (analogue of lamprey GnRH-III, lGnRH-III) linked to tetanus toxoid (using a heterobifunctional reagent to achieve cross linkage). Antibody production, hormone levels and testicular diameter changes were assessed, together with, sperm movement and effects on organ weights. Similar high levels of antibody secretion were observed in all the immunized groups, although whole GnRHI- KLH produced a sustained level of production for an additional week. Similarly, testosterone levels were significantly (p<0.05) reduced in all immunized groups. There were no significant changes observed in body weight and testicular diameter of immunized animals compared with the untreated controls. However, in terms of sperm motility and sperm number, the best anti-fertility effects were observed with lGnRH-III-TT and GnRH-I-KLH and to a lesser extent whole GnRH-I-KLH. These groups also showed significant increase in kidney weight. Finally, considering all the above-mentioned subjects in addition to availability and easier and cheaper way of preparation,we came to this conclusion that whole GnRH-IKLH satisfactorily met most of our favourite criteria and could be used in immunocastration vaccine production purposes successfully