Nutritional quality of mesquite (Prosopis glandulosa) and potential toxicosis in sheep

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Title: Nutritional quality of mesquite (Prosopis glandulosa) and potential toxicosis in sheep
Author: Baptista, Rene
Abstract: Mesquite leaves are emergency forage during dry seasons but they have low palatability . An in vivo digestion trial was completed with lambs (n = 15 ) assigned to diets of 0 , 5 , 10 , 15 , or 20 % mesquite leaves mixed with alfalfa hay to measure effects of mesquite on digestion parameters . Proportion of mesquite leaves in the diet negatively affected dry matter (DM ) intake , nitrogen (N ) balance , gross energy (GE ) intake , retained N , retained GE , and weight gain at levels > 5 % of the diet (P < 0 .01 ) . Mesquite intake was the highest at the 5 % level (1 .81 g /kg BW ; P < 0 .01 ) and averaged 0 .78 g /kg BW for the remaining diets . Coefficient of apparent digestibility (COD ) was not affected by level of mesquite in the diet (P = 0 .58 ) . An in situ Dacron bag trial revealed that pure alfalfa hay was more digestible than mesquite leaves (P = 0 .01 ) . However , %N , acid and neutral detergent fiber (ADF and NDF ) did not differ between mesquite and alfalfa . Low levels of enzymes bilirubin , aspartate aminotransferase , and gammaglutamyl transferase suggested no liver damage (P > 0 .05 ) . Allelochemicals in mesquite were presumably strong intake inhibitors . A conditioned flavor aversion (CFA ) trial tested the effect of postingestive feedback from mesquite on the intake of a novel feed (rye ) . On day 1 , lambs were offered rye and then ground mesquite was infused into their rumens by tube . Lambs (n=21 ) were assigned to dosing treatments 0 (control ) , 3 .0 (low ) , and 4 .5 (high ) g /kg BW of mesquite leaves . On day 3 , lambs dosed with mesquite ate less than controls (P < 0 .01 ) showing a strong CFA . Aversion to rye persisted for at least 2 days (P < 0 .01 ) . The high dose of mesquite decreased the intake of alfalfa ration for at least 3 days (P <0 .01 ) . Persistent diahrrea in lambs receiving the high mesquite dose could be a result of toxins in mesquite . Examination of nutrients in mesquite leaves collected from May to November 1995 , showed an increasing trend for DM from 42 % (May ) to 58 % (November ) . Content of N decreased with season (P < 0 .01 ) , from a maximum of 2 .73 % in May to 1 .58 % in November . Analysis of ADF and NDF indicated similar effect of months (P <0 .01 ) . Minimum content of fiber was found in May , (23 .7 % ADF ; 32 .0 % NDF ) and maximum levels were reached in June (32 .9 % ADF ; 43 .1 % NDF ) . Values of fiber decreased again in November (29 % ADF ; 38 .8 % NDF ) . In vitro digestibility was similar for May and June (79 % ) , and decreased significantly (P <0 .01 ) for the remaining months , from 74 % in July to 69 % in November .
URI: http : / /hdl .handle .net /2346 /10575
Date: 1996-08

Citation

Baptista, Rene Nutritional quality of mesquite (Prosopis glandulosa) and potential toxicosis in sheep. Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /10575 .

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