رسائل ماجيستير
English
2005
Effect of Dietary Choline and Methionine on Broiler Chicks Performance and Some Blood Parameters
بخيت منصور دوسة عبدالرحمن , خديجة عباس عبدالعاطي
كلية الإنتاج الحيوانى-جامعة الخرطوم · السودان
Three levels of dietary energy (9.5, 10.5 and 11.5 MJ/Kg) wereused with a total of 48 Baggara heifers divided into three equal groupseach of 16 heifers, to study the effect of dietary energy onperformance, carcass characteristics, carcass composition, meatquality and meat palatability.The result indicated that dry matter intake ranged between 6.14– 6.8 Kg and was significantly affected by dietary energy level. Drymatter intake was significantly (p<0.01) lower for heifers group fed 11.5MJ/Kg energy level. Daily weight gain ranged between 0.58 – 0.73 Kg,and was also not significant but was superior for the heifers fed 11.5MJ/Kg. While feed conversion ratio was significantly (p<0.01) inferiorfor heifers fed 9.5 MJ/Kg. The result indicated that the slaughter weightranged from (225 – 250) Kg empty body weight ranged from (193 –213) Kg and were significantly affected by dietary energy level. Heifersgroup fed 9.5MJ/Kg energy level had significantly (p<0.05) lighterslaughter and empty body weights. Dressing percentage values wereimproved by the energy level and heifers fed 9.5MJ/Kg energy levelhad consistently the least dressing percentage values. Dressingpercentage of hot carcasses ranged as 52 – 54% when calculated onslaughter weight bases and 61.3 – 62.4% when calculated on empty13body weight bases. For cold carcasses the corresponding dressingpercentage ranges were 50 – 52.6% and 59.6 – 60.5%.The area of the longissimus dorsi muscle ranged from 48.5 –65.2cm2 and was significantly affected by dietary energy level where itwas significantly (p< 0.01) smaller for heifers fed 9.5MJ/Kg energylevel. Back fat thickness ranged from 0.99 to 1.10 cm and wasimproved by dietary energy level, and heifers fed 11.5 and 10.5MJ/Kgenergy level had the thicker back fat.Carcass composition indicated that total carcass musclepercentage ranged from 60.6 to 63.5% and was found to be higher forheifers fed 9.5MJ/Kg energy level. While total carcass fat ranged from14.2 – 17.6% and was found to be lower for the same heifers.The data indicated that increasing dietary energy level resultedin increasing the proportion of high price cuts and heifers fed11.5MJ/Kg energy level produced carcasses with 4.4% more high pricecuts.Eating quality of meat revealed no significant differencesbetween the different groups except for meat obtained from heifers fed11.5MJ/Kg energy level, which was significantly (p<0.05) moreacceptable.14Water holding capacity and p H were significantly (p<0.01)higher in meat from heifers fed 9.5MJ/Kg energy level. While cookingloss was lower in meat from the same group.Hunter colour measurements indicated that meat from heifersfed 9.5MJ/Kg energy level had the highest degree of lightness andsignificantly (p<0.01) lower degree of redness. While meat from heifersfed 11.5MJ/Kg energy level had the least degree of yellowness.Meat chemical composition indicated that meat from heifers fed11.5MJ/Kg energy level had significantly (p<0.01) higher etherextraction. While meat from heifers fed 9.5MJ/Kg energy level hadsignificantly (p<0.01) higher crude protein and non – protein nitrogen.Moreover, it had the highest moisture, ash and myofibillar proteincontent.Correlation coefficient between some carcass measurementscompared with slaughter weight indicated that chest circumference,barrel circumference, total carcass muscle, total carcass bone and totalcarcass fat were low and positively correlated with slaughter weight,while hindquarter circumference was high and positively correlated withslaughter weight.
