Utilization of cassava leaves (Manihot esculenta) as Feed and Natural milk preservative

Abstract

The present study was conducted to investigate the effect of feeding cassava leaves at different inclusion levels and their utilization as a natural milk preservative for Sudanese Nubian goats. The study also included the effect of feeding cassava leaves on some productive characters of Sudanese Nubian goats. A total of 25 Sudanese Nubian goats were used as experimental animals. Initially 12 lactating does were divided into three groups based on matchability in live body weight, age and parity number, and assigned to three cassava leaves inclusion levels (0.0, 15 and 20%) as a preliminary experiment. The results of the preliminary experiment revealed that titratable acidity percentage of the milk of goats fed on 20% cassava leaves was lower than those fed on 0.0% and 15% cassava at 5th ,6th and 7th hour post-milking. Also, it was found that fewer milk samples from the group maintained on 20% cassava showed positive results(spoiled) at the 7th hour after milking, compared to the other two groups ( 0.0, 15 and 20%). The results of the preliminary experiment suggested that cassava leaves inclusions didn't affect the keeping quality of goats raw milk, and there is a possibility of preservative effects if the cassava leaves inclusion increase. Accordingly, cassava leaves inclusion rate (15%) was doubled (0.0%, 20%, 30%). The results of the new inclusion level indicated that titratable acidity percentage of raw milk of goat fed on 30% cassava leaves was significantly (P< 0.05) lower than those raised on 0.0% and 20% cassava leaves at 5th, 6th and 7th hour post-milking. Also, the clot-on boiling results elucidated that milk samples of goats offered 30% cassava leaves was significantly (P< 0.05) better than those fed on 0.0% and 20% cassava leaves at the 7th hour. However, the resazurin reduction test revealed that all samples from the three groups showed disc reading below 4. The results indicated that does fed on 20% cassava leaves produced significantly (P< 0.05) more average daily and total milk yield than the other two groups (0.0% and 20% cassava leaves). Moreover, does fed on 30% cassava leaves were found to be more persistent and tended to reach their peak yield later than the other two groups. Milk fat, protein, total solids, solids not fat and ash% were not significantly (P> 0.05) affected by cassava inclusion levels. Dry matter intake recorded during lactation period revealed that goats maintained on 20% cassava leaves consumed more dry matter (DM), crude protein (CP) and metabolizable energy (ME) than those raised on 0.0% and 30% cassava leaves levels. When dry matter intake was expressed as percentage of live body weight, both does fed on 20% and 30% cassava leaves consumed more DM than those maintained on the control ration (2.3, 2.7, 2.7%). It was observed that goats fed on 30 % cassava leaves gained weight(.5 kg) during the lactation period while those offered 0.0 and 20% cassava leaves lost weights (3.3±1.2 and 2.0±0.4 kg respectively). The same cassava leaves inclusion levels were used to investigate their effects on goats performance during the last 4 weeks of gestation. The results showed that goats maintained on 20% cassava leaves tended to eat insignificantly (P> 0.05) more DM, CP and ME, and also it secured higher daily weight gain (225/g) than those fed on the control ration and 30% cassava leaves. The present results disclosed that, cassava leaves inclusions increased total dry matter intake, and inclusion up to 20% exerted better performance. No deleterious effects were observed when the two cassava leaves inclusions fed during this period (4 weeks prior to kidding). Cassava leaves inclusion levels secured insignificant (P> 0.05) effects on birth weight, the respective recorded averages birth weight for kids in the three groups were 2.3 ± 0.37, 2.3 ± 0.03 and 2.54 ± 0.12kg for the does fed (0.0 ,20 and 30% cassava leaves respectively. Does fed on 30% cassava leaves born slightly heavier kids than those raised on 0.0 and 20% cassava. 13 kids born to the present does were used to investigate the effect of cassava leaves inclusions on kids post-weaning performance (8 weeks post-weaning). The kids were divided into three groups and then assigned to the cassava inclusions (0.0%, 20%, 30%). The results indicated that weaning weights were not affected by the three cassava leaves inclusions. (8.8 ± 1.42, 7.8 ± 0.95 and 8.0 ± 1.0 kg for the three groups respectively). It was observed that kids raised on control ration consumed insignificantly (P> 0.05) more DM, CP and ME than those fed on either 20% or 30% cassava leaves. But, kids maintained on 30% cassava leaves secured the highest daily weight gain (45.3 g) compared to those fed on the control ration (24.4g) and 20% cassava leaves (32.5g) in the same period (8 weeks post-weaning). From the results of the current study, it can possibly concluded that cassava leaves can be safely incorporated into goats rations at a level of 30% without adverse effects on production performance. 20% cassava leaves inclusion gave a better production performance, whereas, 30% level, maintained longer milk shelf-life.