EFFECT OF RUMINAL DEGRADABILITY OF CRUDE PROTEIN AND NON STRUCTURAL CARBOHYDRATES ON THE PERFORMANCE OF LACTATING GOATS: 2. FEED DIGESTIBILITY, SOME BLOOD CONSTITUENTS AND MILK PRODUCTION AND ITS COMPOSITION

El-Shabrawy, H M.; El-Deeb, M. M.; Ismail, M. M.; Mehrez, A. Z.

doi:10.21608/jappmu.2010.86268

EFFECT OF RUMINAL DEGRADABILITY OF CRUDE PROTEIN AND NON STRUCTURAL CARBOHYDRATES ON THE PERFORMANCE OF LACTATING GOATS: 2. FEED DIGESTIBILITY, SOME BLOOD CONSTITUENTS AND MILK PRODUCTION AND ITS COMPOSITION

Document Type : Original Article

Authors

¹ Animal Nutrition Dept.; Animal Production Res. Inst., Agric. Res. Centre, Ministry of Agric., Dokki, Giza, Egypt

² Dairy Technology Dept., Animal Production Res. Inst., Agric. Res. Centre, Ministry of Agric., Dokki, Giza, Egypt

³ Animal Production Dept., Fac. Agric., Mans. Univ

10.21608/jappmu.2010.86268

Abstract

Twenty four lactating Zaraibi goats in mid lactation were used in a 2 x 2 factorial experimental design to evaluate two different sources of ruminally degradable non structural carbohydrates (high and low RDNSC) and two different sources of ruminally degradable protein (high and low RDP). Four experimental diets were formulated to study their effects on digestion coefficients, some blood constituents and milk production and its composition.
The obtained results indicated that digestibility coefficients for DM, OM, CP and NFE and the nutritive value in terms of TDN and DCP% were significantly (P<0.05) higher for goats received low RDP and high RDNSC diets than those received high RDP and low RDNSC diets. The concentration of plasma urea-N was decreased (P<0.05) when goats were fed low RDP diets than those fed high RDP ones, whereas the concentrations of total protein, albumin and globulin were increased indicating once more better utilization of low RDP. Regardless the RDP, plasma urea-N was significantly (P<0.05) lower in goats fed high RDNSC diets than in those fed low RDNSC diets.
Yields of milk, 4% fat-corrected milk (4%-FCM) and milk components were higher (P<0.05) when goats fed low RDP diets than those fed high RDP ones. Milk non-protein-nitrogen (NPN) was lower (P<0.05) with low RDP diets. On the other hand, yield of true protein nitrogen, casein nitrogen, whey nitrogen and unsaturated fatty acids in milk were higher (P<0.05) with goats fed low RDP than those fed high RDP. Regardless the RDP content of the tested diets, a slight improvement in milk yield and 4%-FCM detected for goats given high RDNSC diets compared to those given low RDNSC ones without significant differences. Goats received low RDP with high RDNSC (diet 4) were higher and more persistent for milk yield during the experimental period. On the other hand goats received diets contained high RDP with high RDNSC produced the lowest milk yield.

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