RESUMEN
Forty-five male non-castrated crossbred Dorper lambs (40.17 ± 0.35 kg body weight, BW) were employed in a completely randomized design with five treatments to investigate the effects of the duration of calcium propionate (CaPr) supplementation (10 g CaPr/lamb/d for 0, 14, 28, or 42 d before slaughter) on lambs finished with zilpaterol hydrochloride (ZH, 7.2 mg/lamb/d for a fixed period of 28 d before slaughter) regarding their productive performance, carcass characteristics, and meat quality. Treatments consisted of the following: (1) No additives (CTL), (2) 0 days on CaPr plus 28 d on ZH, (3) 14 days on CaPr plus 28 d on ZH, (4) 28 days on CaPr plus 28 d on ZH, and (5) 42 days on CaPr plus 28 d on ZH. When compared with CTL, ZH lambs exhibited a similar average daily gain (ADG) but had lower dry matter intake (DMI), leading to increased feed efficiency. Supplementing with ZH alone did not affect carcass traits, visceral mass, whole cuts, or meat quality. Lambs that received both CaPr 28 d and ZH exhibited quadratic increases (p < 0.05) in final body weight (FBW), ADG, and dressing percentage (D%). These increases were optimal at estimated inclusion durations of 26 d for FBW, 30 for ADG, and 39 d for D%. The ADG:DMI ratio and the longissimus muscle area (LMA) both exhibited quadratic increases (p < 0.05). The optimal duration of CaPr supplementation for ADG:DMI ratio was found to be 28 d, while for LMA, it was 14 d. As the period of CaPr supplementation increased, there was a linear increase (p < 0.05) in hot carcass weight, leg circumference, and whole cuts of breast IMPS209 and shoulder IMPS207. Cook loss percent increased quadratically (p < 0.05), and was higher when CaPr was included for an estimated duration of 26 d. As the duration of CaPr supplementation increased, the purge loss percentage (PRL) also increased linearly (p < 0.05). In conclusion, including CaPr in the diet for a duration of 28 d in lambs improved the response to ZH supplementation on the productive performance, carcass weight, and some whole cuts. However, it can also have a negative effect on PRL%.
RESUMEN
ABSTRACT: One hundred eighty-nine Catalan crossbreed donkeys (Equus africanus asinus) were used to evaluate the effect of gender (gelding, n=106; or female, n=83) and live weight at slaughter (LW) (<100kg, n=25; 101 to 125kg, n=42; 126 to 150kg, n=85; and 151>kg, n=37) on carcass characteristics, non-carcass components and meat and fat color. Geldings had greater (P<0.05) carcass weight, carcass dressing and *L value of subcutaneous fat than females; but females had greater (P<0.05) cooling loss, a* value of semitendinosus muscle and b* value of subcutaneous fat. Donkeys with more than 126kg of LW showed greater (P<0.05) carcass weight and dressing and lower (P<0.05) cooling loss compared to lighter donkeys. The a* value of semitendinosus muscle and abdominal fat was greater in heaviest donkeys (>151kg). Meanwhile, the LW did not affect the color (L*, a* and b* values) of subcutaneous fat (P>0.05). These results suggested that both gender and live weight should be considered when producing meat from donkeys. It is advisable to use geldings weighing more than 126kg at slaughter to obtain the greatest weight and carcass yield.
RESUMO: O objetivo deste estudo foi avaliar o efeito do gênero e peso vivo (PV) nas características da carcaça, componentes não-carcaça e cor da carne e gordura dos burros (Equus africanus asinus). Foram utilizados 189 animais de sexo castrado ou feminino. Os castrados tiveram peso de carcaça maior (P <0,05), molho de carcaça e uma gordura subcutânea luminosa (valor L) nas fêmeas. As fêmeas apresentaram perda de resfriamento maior (P <0,05), *valor de cor do músculo semitendinoso e b* valor de cor da gordura subcutânea. A gordura subcutânea apresentou maior (P <0,05) b* em animais idosos. Os burros com mais de 126kg de PV apresentaram maior peso de carcaça (P <0,05), curativo de carcaça e menor (P <0,05) perda de resfriamento em comparação com burros mais leves. O músculo semitendinoso e a gordura abdominal foram avermelhadas (P <0,05), maior valor de *, em burros mais pesados (>151kg). Enquanto isso, o PV não afetou a cor (valores de L *, a * e b *) de gordura subcutânea (P> 0,05). O peso maior da carcaça e o curativo com efeitos limitados em componentes não carcaça, cor de carne e gordura foram observados em castrados com peso vivo superior a 126kg.
RESUMEN
This study evaluated whether the administration of 50 and 100 mg bovine somatotropin (bST) at the start of estrous synchronization and at the time of artificial insemination improves lambing rate and prolificacy in hair sheep. Four hundred eighty adult hair ewes (Pelibuey, Blackbelly, Dorper, Katahdin, and their crosses) were synchronized with intravaginal sponge containing 40 mg of fluorogestone acetate. On the day of sponge insertion, ewes were assigned to three treatments: the bST-100 treatment (n = 156) received 100 mg bST at the start of synchronization (d 0) and at the time of insemination (d 14), the bST-50 treatment (n = 159) received 50 mg bST in the same schedule as the previous group, and the control (n = 165) did not receive any bST. Lambing rate and percentage of multiple births were analyzed using the GENMOD procedure of SAS. Prolificacy data were analyzed using the MIXED procedure of SAS. The IGF-1 and insulin concentrations were analyzed with ANOVA for repeated measures. The bST application did not affect the lambing rate (P = 0.06). The proportion of ewes with multiple births (P = 0.01) and prolificacy (P = 0.04) were higher in the bST-50 (54.3% and 1.57 ± 0.1) than the bST-100 (18.2% and 1.25 ± 0.1) and control (33.3% and 1.28 ± 0.1) groups. The IGF-1 and insulin concentrations were higher (P < 0.05) in the bST-treated groups, but the insulin concentration was higher (P = 0.001) in the bST-100 group than in the bST-50 group. The administration of 50 or 100 mg bST at the start of synchronization and at the time of artificial insemination does not increase lambing rate. However, the dose of 50 mg increased the proportion of multiple births and prolificacy.
