carcass compositions

Crossbreeding as the fastest approach to take advantage of difference between breeds, can be an effective method to improve the efficiency of meat production in sheep. The aim of the present study is to compare Balochi lambs with the crossbred obtained from Baluchi ewes with Kurdi and Karakul rams.

In order to investigate the effect of crossbreeding on the weight performance of lambs up to weaning and the fattening period and carcass composition, three genetic groups including pure Baluchi (BB) lambs, Karakul × Baluchi (GB) and Kurdi × Baluchi (KB) crosses were used. The ewes were mated in groups of 50 and each group with 2 rams. The number of 27 purebred and crossbred male lambs were used in the form of three treatments with three replications and three lambs per replication. Data were analyzed using GLM procedure of SAS software.

The results showed that lambs from Karakul rams had the highest birth weight and lambs from Baluchi rams had the lowest birth weight (4.80 and 3.95 kg, respectively). Lambs from karakul rams had higher daily gain (260g /day) before weaning than other lambs (p<0.05).  The highest and lowest dry matter intake were in the GB group (1250g /day) and the BB group (950 g / day), respectively. The highest daily gain in GB group and the lowest in BB group were 169.2 and 93.8 g / day, respectively (p <0.05). The genetically groups had significant effect on cold and hot carcass weights (p<0.05). The effect of crossbreeding on fat thickness, fat-tail, and shank was significant (p<0.05).

Due to the suitable reproductive performance in using Karakul ram as a paternal breeding base and optimal performance in growth rate, feed consumption, conversion ratio in the pre-weaning and post-weaning periods as well as carcass characteristics including hot and cold carcass weight and less tail compared to other crossbreds used in this study, it is probably more appropriate to use Karakul rams to produce crossbred lambs.

The aim of this study was to evaluate the effect of crossbreeding on growth performance and carcass composition of purebred and crossbred Kurdilambs. Thus, two genetic groups including purebred Kurdi lambs (KK) and crossbred Kurdi*Romanov lambs (KR) were used. For analysis of carcasstraits, six lambs from each group were selected and slaughtered. The number of weaned lambs for KK and KR were 95 and 45, respectively. Ourresults indicated thatKK purebred lambs had the highest (4.5 kg) and KR crossbred lambs had the lowest (4.1 kg) birth weight (P < 0.05). CrossbredKurdi*Romanov lambs had higher average daily gain than KK purebred lambs (P < 0.05). The means of final weights of purebred lambs weresignificantly higher than crossbred lambs (54.8 vs. 41.5 kg, respectively). The genetic groups had no significant effect on cold and hot carcass weights.The effect of crossbreeding on fat thickness, fat-tail and leg was significant (P < 0.05). Crossbred lambs performed better than purebred lambs in thepre-weaning period, but purebred Kurdi lambs performed better than crossbred lambs in the fattening period. In general, it can be reported that thecrossbreeding of Kurdi sheep with Romanov sheep did not show the desireble results.

This experiment was conducted to compare the effects of quantitative feed restriction and meal feeding on the performance, carcass compositions and ascites syndrome in male broiler chickens (Ross 308). In this study, 5 Schedule feed restrictions include: 1) ad libitum food intake (AL group), 2) feeding maintenance energy requirement from 7 to 14 d of age 3) feeding to support 50% of the normal growth energy requirement from 7 to 14 d of age 4) meal feeding from 7 to 14 d of age (MF14) and 5) meal feeding from 7 to 21 d of age (MF21), were used. Three hundred day-old male broilers in a completely randomized design (with five treatments, five replicates per treatment and 12 birds per pen) were raised until 42 days. At the age of 21 d the chickens were exposed to a temperature of 15°C, which induced ascites. Traits measured included performance, carcass characteristics and parameters of the heart and blood. The results indicated that quantitative feed restriction reduced weight gain and feed intake compared to AL group (P<0.05). At the end of experiment, feed conversion ratio of MF14 group was less than fed group for 50% growth (P<0.05). Feed restriction had no significant effect on percentage of carcass composition (carcass, breast, thigh and abdominal fat). AL and MF14 broilers had high hematocrit and hemoglobin concentration. MF14 group compared with the quantitative feed restriction groups had a greater heart weight (P<0.05). Ascites index (RV/TV ratio), right ventricle weight and percentage of heart were not affected by feeding regimes. The overall results showed that less severe restriction (meal feeding treatments) on compared with more severe restriction (quantitative feed restriction treatments) was better to realize the complete compensatory growth. According to blood factors, severe feed restriction can decrease ascites susceptibility in broiler chickens.

This experiment was conducted to investigate the effect of diet and fattening start weight on body growth in the different stages of the fattening periods and carcass compositions of Moghani male lambs. For this purpose, 36 heads of Moghani male lambs with three weights classes (Light, medium and heavy weight) were used with two diets (alfalfa to concentrate ratio of 70 to 30 (diet 1) and 30 to 70 (diet 2)) were fattening up to the time which their weights were 55 kg. The lambs were placed in individual cages for control the amount of feed daily intake and residual collected. The diets of high concentrate compared with diet of high forage were more favorable effect on body weight during the fattening at all stages and also daily weight gain (P<0.05). The significant difference was between heavy weight lambs (112 g/day) with light weight lambs (153 g/day) on daily weight gain (P<0.05). The diet had significant effect on carcass efficiency, hot and cold carcass weight, fat-tail weight and liver weight (P<0.05) and also percentage of fat-tail weight to carcass weight ratio (P<0.05). Negative correlation existed between fat-tail weight with different component of the carcass, especially with its valuable parts (leg, sirloin, breast and shoulder). Generally, high concentrate intake caused increase of fat-tail stores. Fattening with low weight increased daily weight gain, but in higher age was associated with fat stores in Moghani male lambs.