الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 154 |  |  |
| | | from | 154 | | |
Abstract
Total of 15 local breed (Zaraibi) and 15 exotic breed (Damascus) goats were used in this study. Animals are 2-5 years old and mating in September mating season and their average body weight at the beginning of study was 41.041.19 kg and 55.711.71 kg for Zaraibi and Damascus, respectively. Goats separated due to their parity, group 1 in the 1st parity (5 Zaraibi + 5 Damascus) (G1) ; goats in group 2 in the 2nd parity (5 Zaraibi + 5 Damascus) (G2) and goats in group 3 in the 3rd parity (5 Zaraibi + 5 Damascus) (G3). All animals were kept under similar management conditions. Four batches of soft cheese (Dani cheese) were made from milk of goats of the two breed groups. Twenty kg of milk taken at mid and late lactation period (July-August) were used for each batch. Milk of all batches was heated to 72oC for about 15 seconds, cooled to 37oC, salted at 6% and then treated with rennet only or with rennet + starter constant of (Streptococcus thermophilus and Lactobacillus delbruckii sub sp. Bulgaricus). Resultant cheese of all groups were pickled into their own whey after raising its salt content to 8%, and stored in tins at 5oC for 2 months. Fresh cheese yield was recorded. Samples of cheese were taken for chemical analysis (pH, titratable acidity, Fat, TS, TN, NPN, SN, salt, TVFA, Tyrosine and tryptophan) when fresh and biweekly during pickling. The obtained results could be summarized as following :• Milk yield was slightly higher in both Zaraibi and Damascus goats in 2nd and 3rd parity than that in the 1st parity. Milk yield for Zaraibi goats slightly increased but in fewer rates between week 8 up to week 10, then the milk yield declined up to the end of lactation. On the other hand, Damascus goats showed the same trend of slight increase in the period between week 10 up to week 14. Rates of marked decrease in milk yield (<1 kg/day) for Zaraibi and Damascus goats of 1st, 2nd and 3rd parity start from week 20 up to end of lactation (week 30), except for Damascus and Zaraibi goats on 3rd parity, which markedly decreased in milk yield (<1 kg/day) from week 24 up to the end of lactation.• Lactation period was longer for Damascus goats (168 days) than for Zaraibi goats (126 days) of all parities. During the lactation period, Zaraibi goats yielded milk 105.0, 114.8 and 140.84 kg for 1st, 2nd and 3rd parity, respectively with significantly higher differences between 3rd parity than 1st and 2nd parity. While Damascus goats yielded milk 172.48, 183.12 and 229.6 kg for 1st, 2nd and 3rd parity, respectively with significantly higher differences between 3rd parity than 1st and 2nd parity.• Results indicated that total solids content of milk were almost similar during the first stage of lactation (2 months), thenafter decreased gradually up to (4 months) and gradually increased up to the end of lactation period (6-7 months). Also, it could be noticed that goats on 3rd parity showed higher total solids content than that of the other two parties groups. But on the stage (6-7 months) Zaraibi and Damascus goats on 2nd party have the higher total protein content than the other two parties groups.• It could be observed that the salt content significantly (P<0.05) higher in fresh cheese made from Damascus milk with starter + rennet than in Zaraibi cheese made from rennet alone (5.40 vs. 4.70).• Fat content of cheese made from milk of Damascus goats was significantly (P<0.05) lower than that of Zaraibi goats, only in fresh cheese made with rennet and after 15 days of pickling. However, fat content was almost higher in cheese of both breeds made by using starter + rennet than with rennet only whether fresh or during the pickling period.• There were marked differences in total protein content in cheese of both goat breeds either made with the addition of rennet alone or rennet together with starter. Total protein content was almost significantly (P<0.05) higher in Damascus than in Zaraibi cheese. Also, there was marked decrease in protein content only in Damascus cheese made by using rennet alone, as compared to that made by using starter + rennet.• There were no significant differences in S.N./T.N. content in fresh cheese of both goat breeds either made by using rennet alone or rennet together with the starter. Content of S.N./T.N. was significantly (P<0.05) higher in Damascus than in Zaraibi cheese only after 45 days of pickling of cheese made by using rennet alone or rennet together with starter. The present results concluded that Damascus goats are characterized as a high milk producer, so, they used in crossing with the local breeds of goats (Barki and Baladi). Goat’s milk production during 6-7 months of lactation period for the third parity is considered as the best period for milk yield and composition and the best yield cheese and composition using rennet or rennet with starter for coagulating goat’s milk.