ملخص رسالة الدكتوراه الخاصة بالدكتور/ محترم عبدالله محمد ابراهيم

عنوان الرسالة

Effect of weaning system on productive and reproductive performance of Rahamani and Chios sheep under upper Egypt condition

(قسم الانتاج الحيوانى والدواجن - زراعة الازهر باسيوط)

الاسم / محترم عبدالله محمد ابراهيم

كلية الزراعة - جامعة الازهر باسيوط

ممنوحة من/ قسم الانتاج الحيوانى والدواجن - كلية الزراعة - جامعة اسيوط

بتاريخ 9/6/2009

بريد اليكترونى/ [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]
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Mobil// 0106957157

Summary

The present study was, therefore, an attempt to apply systems of weaning using a lamb starter ration, for Chios and Rahmani lambs maintained in Animal production Farm belonging to Faculty of Agriculture, AL–Azhar University under the environmental of Assiut condition. The effects of such systems and age at weaning on growth rate, survival rate, efficiency of feed utilization, and characters of carcass of Chios and Rahmani lambs, were studied in details throughout the present investigation. Also, this study aimed to evaluate some productive and reproductive traits in Rahmani and Chios ewes.

The results obtained from the analysis of the data can be summarized as follows:

Body weight of lambs

There was no significant effect of weaning system on birth weight Chios lambs were heavier at birth than Rahmani ones. Males were heavier (P<0.01) at birth compared to females weighing. Season of lambing was not significant effect on birth weight; Lambs born in summer averaged 0.130 kg heavier than those born in winter at birth. Age of dam was not significant effect on birth weight.

Body weight of lambs influenced significantly (P<0.01) by weaning system at 3 and 4 months. After weaning, the three weaning system did not differ significantly in weight up to one year of age. Breed of lambs has significantly (P<0.01) influenced lamb body weight at all stages of growth. However, Chios lambs tended to be heavier than Rahmani lambs. Male and single born lambs were heavier significantly (P<0.01) than female and twins born lambs at all ages studied. Lambing year significantly affected body weight at all ages studied except at one year of age. Season of lambing and age of dam had not significant effect on weights of lambs.

Average daily gain:

Weaning system was a significant effect on average daily gain at all periods studied except from birth to one year of age. While, There was no effect of weaning system on total gain. Breed of lambs did not differ significantly in average daily gain and total gain at all periods of the study. Sex of lambs had a significant effect on daily gain from birth to 2 month and from 6 to 9 month. Male lambs have attained total gain heavier significantly (P<0.05) than female lambs. Single born lambs had a significantly higher (P<0.01) average daily gain from birth to 2 month, from birth to 3 month and from birth to 4 months of age compared to twins. Single born lambs and twins were not significantly different in average daily gain in other periods.

Year of lambing had a significant (P<0.01) effect on average daily gain of lambs at periods from birth to 2 month, from birth to 3 month, from birth to 4 month and from 9 to 12 months of age. Season of lambing had no significant effect on average daily gain of lambs at all periods studied except from 6 to 9 months and from 9 to 12 months of age this effect was a significant. Age of dam had a significant effect on average daily gain at period from birth to 2 month and from 6 to months of age, but not significant at other periods studied.

Survival rate of lambs:

Survival rate was not significant affected by weaning system during all growth periods. Rahmani had a more survival rate than Chios lambs at birth and at 30 days of age, the differences were not significant. Sex of lambs was not significant during all growth periods except at 60 days of age, the survival rate of male lambs was significantly higher than female lambs. Single born lambs had a higher (P<0.01) survival rate than twins at birth, 30 and 60 days of age (P<0.05). However, twin born lambs had maintained their high survival rate after first month to yearling. Effect of lambing year and season on survival rate were not significant at all periods studied. Age of dam had a significant effect on survival rate of lambs at birth, 30, 60 and 120 day of age. Regression coefficient of survival rate on birth weight showed that birth weight had a highly significant effect (P<0.01) at all periods studied.

Body measurement of lambs:

Weaning system had a significant effect on body length at 90 day, wither height at 90, 180 and 270 day, thigh length at 270 and 365 day of age and tail volume at 270 day of age. Breed of lambs affected significantly on body measurements at all periods study except on canon length, as well as on tail measurements except on tail volume. Single born lambs had a significantly (P<0.01) higher in heart girth and chest depth than twin born lambs at 90 day of age, also, significantly higher body length and chest depth at 365 days of age.

At 90 days of age male lambs were significantly (P<0.05) higher of chest depth, thigh length and wither height than female lambs. While, sex of lambs was not significant affect on body measurements at 180, 270 and 365 days of age.

Age of dam had a significant effect on heart girth at 90 and 180 days of age, body length, thigh length, canon length and wither height at 270 days of age, and on canon length at 365 days of age. Age of dam was not significant effect on other body measurements and tail measurements at all stages. Correlation coefficients among the various body measurements and live body weight of Rahmani and Chios lambs at one year of age were strong and positive.

Blood constituents of lambs:

After birth, weaning system, breed, sex, type of birth and season were did not effect on blood constituents except influence of breed on triglyceride and season on globulin and cholesterol levels was a significant.

Weaning system had a significant effect on plasma protein, breed of lambs had a significant effect on triglyceride and glucose level at pre-weaning period, also, season had a significant effect on protein, albumin, globulin and cholesterol level.

After weaning, A/G ratio, ALT, AST, cholesterol and glucose level affected significantly by weaning age, breed of lambs had a significant effect on albumin and A/G ratio. Male lambs were higher significantly A/G ratio and triglyceride than female. Also, post weaning triglyceride and cholesterol level were higher significantly (P<0.01) in winter than summer.

At one year of age, weaning system had a significant effect on plasma protein, globulin, A/G ratio, ALT, AST and glucose level. Chios lambs had significantly higher AST and glucose level. Sex of lambs and birth type were not significant effect on blood constituents except A/G ratio affected significantly by breed. Plasma protein, globulin, A/G ratio, ALT, AST and triglyceride influenced significantly by season.

Reproductive performance of lambs:

Breed of ewe lambs had a significant effect on age, weight at puberty, age at maturity, age at first lambing and estrus cycle length. Chios ewe lambs reached puberty and maturity at younger age and heavier body weight than Rahmani ewe lambs. No significant difference in gestation length between Rahamni and Chios ewe lambs. The effect of birth type and weaning system on reproductive traits of ewe lambs was not significant. Early weaned lambs reached puberty and maturity earlier than normal and late weaned lambs.

Breed of lambs, birth type and weaning system were not significant effect on age and weight at puberty of ram lambs, except age at puberty was affected significantly (P<0.05) by weaning system.

Fattening performance of male lambs:

DMI was higher for Rahmani than Chios lambs. Added Chios lambs were not significantly increased TDNI, CPI and MEI compared with Rahmani lambs. The differences between two breed in digestibility of nutrients (DM, OM, CF and NFE) were significantly higher (P<0.05), while this difference in CP and EE was not significant. The feeding value of TDN, DCP % and ME was increased in Chios than Rahmani lambs. No significant difference in nitrogen balance were found between breeds.

DMI by early weaned lambs drawn near in comparison with the corresponding normal and late weaned group (906 vs 977 and 963 g/h/day, respectively). TDNI, CPI and MEI were higher slightly in both two groups' early and normal weaned lambs than late weaned lambs. higher (p<0.05) nutritive values in different terms for the same ration by early weaned lambs. Utilization of dietary nitrogen indicated higher nitrogen intake NI by normal weaned lambs due to the higher DMI, while digestible nitrogen DN of early weaned lambs was higher than late weaned lambs.

There was no significant difference in body weight through the fattening period between Chios and Rahmani lambs. The difference in total gain and average daily gain between Chios and Rahmani lambs had a significant (P<0.05). However, the Chios lambs had higher average daily gain than Rahmani lambs. Chios lambs had the higher values of body gain related to the units of DM,TDN, and more efficient in kg DCP consumed per kg gain than Rahmani lambs. Chios lambs showed lower cost of feed /1kg gain than Rahmani lambs during the whole experimental periods.

The performance of early, normal and late weaned groups during fattening period, showed that lambs weaned at 8 weeks of age had the same growth rate as un-weaned lambs. DMI/kg gain was higher for late weaned group compared with the early and normal weaned lambs (6.67 vs 6.02 and 4.88, respectively) with insignificant difference between them. Also, efficiency of TDN and DCP intake were found higher for early weaned group than normal and late weaned lambs. feed cost decreased by 23.45 and 36.86 % whereas economical efficiency improved by 18.97 and 26.94 for early weaned lambs compared to the normal and late weaned lambs.

Carcass characteristics:

Non edible offal’s:

Chios lambs were heavier at slaughter and heavier empty body weights than Rahmani lambs, but the difference was not significant. Breed group had a significant effect on Lungs & trachea weight and percentage (P<0.05). Chios lambs had the higher skin, head and feet weights than Rahmani lambs, in contrast, Rahmani lambs were higher in percent of this parts than Chios lambs and the differences due to breed group were not significant. Rahmani and Chios lambs have also differed insignificantly in fresh weights and proportion to carcass of internal organs (GIT). Chios lambs seem to have insignificantly larger gastro-intestinal tract compared to Rahmani.

Early weaned lambs were heavier at slaughter and heavier empty body weights than normal or late weaned lambs. No significant differences were observed in weights or percentages of non-edible parts between three weaning systems, also, early weaned lambs were higher weight of this parts than normal or late weaned lambs. Parts of gastro-intestinal tract (GIT) full or empty weights were higher in lambs weaned at 8 week of age than those weaned at 12 or 16 week, the differences were not significant.

Carcass traits and edible offal’s:

No significant difference found between Rahmani and Chios lambs in hot carcass weight, fast dressing and empty dressing. Chios lambs had a significant (P<0.05) heavier carcass weight without tail and fast dressing without tail than Rahmani lambs. Chios lambs had the higher significantly weights of spleen weight, spleen percent, kidneys weight, kidney fat percent, bowel fat weight and bowel fat percent. But the differences due to breed were not significant on other offal's (liver, heart, tests, kidney fat and total edible offal's).

Weaning system effects on hot carcass weight, fast dressing, fast dressing without tail and empty dressing were not significant. Carcass weight without tail was significantly (P<0.05) affected by weaning system. Age at weaning was not significant effect on liver, spleen, kidneys, heart, tests and total edible offal's weight. Early weaned lambs seem to have larger weights of these parts than normal and late weaning lambs. Also, early weaned lambs have significantly higher bowel fat and kidneys fat weight.

Wholesale cuts:

Chios lambs had significantly (P<0.05) higher in weights of left side, fore shank, loin, flank, and leg weights than Rahmani lambs. Also, Chios lambs had higher weights of shoulder, ribs, breast, sirloin, hind shank and neck, but the differences were not significant. On the other hand, Rahmani lambs had higher significantly tail weight and tail percentage than Chios lambs.

Age at weaning effects on loin, flank, neck and tail weights were a significant (P<0.05), while they were not significant for other wholesale cuts studied. Proportion of loin, flank and tail fat were higher in early weaned lambs than normal or late weaned lambs. Normal weaned lambs were higher insignificantly in percentages of ribs, breast, leg, hind shank and neck, while late weaned lambs were higher significantly (P<0.05) in sirloin and prime cut percent.

Carcass measurements

Carcass from Rahmani lambs was smaller than those from Chios breed. High significant differences (P<0.01) were observed for carcass length, carcass chest girth, carcass chest depth, and carcass thigh circumference, while, breed of lambs was not significant effect on carcass thigh depth. Carcass measurements were not affected by age at weaning.

Ultrasonic measurements and (WHC):

The data regarding longissimus dorsi muscle area and backfat thickness for Rahmani and Chios lambs were found to be (13.3 cm2 and 14.0 cm2) for eye muscle area and (1.54 and 1.91 mm) for backfat thickness, respectively. The average values for backfat thickness, area and depth of eye muscle measured by ultrasound were 1.19 mm, 8.58 cm2 and 17.2 mm, for Rahmani lambs and 1.58 mm, 10.2 cm2, and 20.3 mm, respectively. Eye muscle weight and eye muscle length were higher significantly (P<0.05) in early weaned lambs (0.75 kg and 61.8 cm) than normal (0.65 kg and 54.5 cm), and late weaned lambs (0.51 kg and 56.7 cm), respectively. On the other hand, ultrasonic fat thickness and carcass fat thickness (mm) was higher insignificantly in late weaned lambs than both early and normally weaned lambs.

Breed group effects on WHC were not significant. No significant difference were observed between three weaning system studied.

9, 10 and 11th ribs cut

Weight of 9, 10 and 11th ribs of Rahmani lambs were higher than Chios, but the differences due to breed were not significant. The same trend was observed for samples of meat weight, bone weight, meat percentage, boneless meat, and meat:bone ratio, while, fat weight, fat percentage and bone percentage was higher insignificantly in Chios lambs than Rahmani. Coefficient of meat was slightly higher in Chios than Rahmani lambs, the difference due to breed effect were not significant. There was a non-significant increase in all physical characters values of 9, 10 and 11th ribs cut with increasing age at weaning except fat weight were different significantly (P<0.05) between three weaning system.

Meat composition

The percentage of moisture, fat and ash was slightly higher in Rahmani than Chios. In contrast, Chios lambs had higher protein percentage than Rahmani lambs. Difference due to breed group was not significant. Effect of weaning system on percentage of moisture, protein, fat and ash were not significant.

Reproductive performance of ewes:

Chios ewes were slightly higher fertile than Rahmani ewes, the differences between breeds were not significant. On the other hand, highly significant (P<0.01) differences were found between both breeds in their fecundity, lambing rate and weaning rate. There was no significant difference between seasons of mating in fertility traits. Autumn season was the best season in fertility (88%) compared to (86%) in summer and (87%) in winter season. Year of mating affected the fertility traits were not significant. Fertility traits tended to increase with advancing age of the ewes. Age of ewe had a significant effect on fecundity, lambing rate and weaning rate.

Breed of ewes had a highly significant (P<0.01) effect on prolificacy traits. Chios ewes had a higher litter size at birth, litter size at weaning, litter weight at birth and litter weight at weaning than Rahmani ewes. The differences between seasons were not significant effect on prolificacy traits. No significant differences in prolificacy traits have been observed among both mating year. Prolificacy traits were influenced significantly (P<0.05) by ewe age at mating, but no significant effect were observed on litter weight at weaning.





Milk yield and composition:

The differences between breeds, type of birth and lambing season were significant effect on average daily milk, total milk yield and lactation length. While, ewe age was not significant effect on milk yield and lactation length. Rahmani and Chios ewes reached maximum yield at the 5th week of lactation, after attaining the peak, milk yield decreased gradually till the end of lactation period.

Ewe breed influenced significantly percentage of fat, SNF and milk energy. While, Total solids, percentages of protein, Acidity, PH and Ash were slightly higher in Chios than Rahmani, but the difference was not significant.

Lambing season was not significant effect on milk fat, the same trends were found with acidity and milk energy. Age of ewe had a significant effect on fat percentage followed by milk energy. On reverse, no significant difference were observed of ewe age on percentage of TS, SNF, protein, acidity, PH and