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A crossbreeding experiment involving four Iranian fat-tailed sheep breeds, namely Kurdi (K), Chaal (C), Afshari (A) and Sanjabi (S) was carried out to determine the ram breed effects on productivity of Kurdi fat-tailed ewes (K) under extensive production system. A total of 475 Kurdi ewes were mated to 24 rams from four breeds producing 454 lambs including pure Kurdi, KK, (116 lambs), Afshari × Kurdi, AK, (113 lambs), Chaal × Kurdi, CK, (115 lambs) and Sanjabi × Kurdi crossbreds, SK, (110 lambs). Ram breed had a significant influence on early growth traits of the lambs (P < 0.01). The lambs sired by C rams were significantly heavier at birth and weaning than the other lambs (P < 0.05). Weight at 180 days of age (W180) in crossbred lambs was significantly higher than that of the purebred lambs (P < 0.05) while there was no significant difference among crossbred lambs for W180. Greasy fleece weight of lambs at first shearing (GFW) was significantly affected by ram breed (P < 0.05). Ram breed significantly influenced the fat-tail measurements of the lambs (P < 0.01). Number of lambs born and number of lambs weaned per ewe lambed or per ewe joined were not significantly influenced by ram breed effect, but the effect of ram breed on litter weight at birth and weaning per ewe lambed or per ewe joined was significant (P < 0.05). In general, ewes mated to Chaal ram had higher productivity than those mated to other ram genetic groups.

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Some factors affecting crude protein balance (CPB), as a measure of efficiency, were studied using 2824 records of 501 lactating Holstein cows. The CPB (kg d-1) was calculated as crude protein (CP) intake (kg) minus CP yield (kg). Two different statistical methods including principal components (PCs) and general linear model analyses were used to study the effects of different factors. Crude protein balance had a moderate correlation with PCs 1 (-0.206), 2 (0.318) and 3 (-0.281), which accounted for 65.6% of total variations. Age, parity, lactation stage, pregnancy stage, dry matter intake (DMI), milk yield (MY), fat corrected milk yield (FCM), milk fat percentage (F%), milk lactose percentage (L%), milk fat yield (FY), milk protein yield (PY), milk lactose yield (LY), dietary levels of net energy for lactation (NEL), CP, ruminally undegradable protein (RUP), neutral detergent fiber (NDF) and ether extract (EE) and income over feed cost (IOFC) were correlated to CPB, at least, in one of PCs 1, 2 or 3. In general, linear model analysis CPB was significantly affected by parity and lactation stage and had significant partial linear regression coefficients on DMI (kg d-1), F%, FY (kg d-1), PY (kg d-1), NEL (Mcal kg-1) and dietary levels of CP (%), RUP (%), NDF (%) and EE (%). The quadratic partial regression coefficients of CPB on NEL, CP, RUP and NDF were also significant. The estimates for optimum dietary levels of NEL, CP and RUP for minimizing CPB in the studied population were 1.49 Mcal/kg, 11.29% and 7.58%, respectively. In comparison to NRC’s estimates, it seems that, more NEL, RUP and NDF and less CP are needed to minimize protein balance in lactating dairy cows.

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The possibility of in vivo carcass trait prediction using the ultrasound measurements obtained between 12^th and 13^th ribs was studied. Attention was paid to several carcass traits such as carcass backfat thickness (CBFT), carcass longissimus dorsi muscle (CLMA) and carcass weight (HCW). Also, the effects of the flock, as the fixed effects, and body weight (BW), as covariate, on these traits were considered. The study was carried out on 99 lamb of Torki-Ghashghaii breed from 4 flocks. BW had significant effects (P< 0.001) on HCW, Fat-tail, CBFT, and CLMA, but had no significant effect on carcass longissimus dorsi muscle depth (CLMD) and width (CLMW). The flock had a significant effect (P< 0.0001) on HCW and CBFT, only. The correlations between ultrasound and carcass measurements, before and after adjustment for flock effect, ranged between (0.27 to 0.80) and (0.22 to 0.78), respectively. Estimates of CBFT, CLMW, CLMD and CLMA based on the corresponding ultrasound measurements explained 49%, 29%, 59%, and 64% of their variation, respectively. BW explained 57% variation of HCW and only 12% variation of Fat-tail. The introduction of two or three ultrasound measurements by stepwise procedure in the multiple regression equations improved the explanation of variation for all traits by 0.01 up to 0.13. The results indicate that ultrasound has potential for carcass traits prediction in live Torki-Ghashghaii sheep.