No abstract

No abstract

One hundred thirty New Zealand White x California rabbits were used to study the influence of the source of dietary fiber on several digestive criteria. Five diets were formulated to provide 10% crude fiber (CF) on a DM basis. Sixty percent of this dietary fiber was supplied by alfalfa hay, citrus pulp, beet pulp, grape marc, or rice hulls in the diets. Weights of cecal contents, cecal ammonia concentration, and molar proportion of acetic acid in diets including pulps were higher and cecal levels of DM, CP, and molar proportion of butyric acid were lower than those of the alfalfa diet. Cecal ammonia, VFA, and CF concentrations of the grape marc diet were the lowest of all the diets studied; cecal CF level and molar proportion of acetic acid were significantly higher and CP level and molar proportion of butyric acid were lower in rice hull than in alfalfa diets. Diet had no influence on daily soft feces excretion (10 g DM/d), but N contribution of soft feces to N intake was higher in the diet with citrus pulp (18.7%) than in the other diets (12%). Mean retention time (R) was measured using fuchsin-stained feed and was found to be higher (21.3 h) in the rice hull diet and lower (9.3 h) in the grape marc diet than in the other diets. When coprophagy was prevented, R decreased by 0 to 7 h. In conclusion, the use of byproducts to substitute for traditional sources of fiber in rabbit diets influenced the retention time of the digesta in some segments of the gut and thus altered several digestive criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Two hundred ten Californian x New Zealand White rabbits were used to study the influence of diet and slaughter weight (2.0, 2.25, and 2.5 kg) on feed intake, growth, feed efficiency, carcass characteristics, and body chemical composition. Seven diets were formulated to contain 24% ADF: Diet C (control) had no added fat; Diets T, O, and S contained 3% of added beef tallow, oleins, and soybean oil, respectively; Diets TWS, OWS, and SWS contained the same level and types of fat plus 18% heated whole soybeans (WS) to increase the dietary fat by 3%. Fat addition did not affect ADG or dressing percentage, but it improved feed:gain ratio (.06 for each 1% of dietary fat, P < .001). Although the main measurements of carcass were not influenced by fat addition, the rabbits fed diets containing the highest fat percentage had the highest weights of perirenal (P < .001) and scapular (P < .01) depots and the highest body fat content (P < .01). The increase in slaughter weight improved all the desirable carcass characteristics measured but imparied feed:gain (by 13%, P < .001). Increasing slaughter weight also increased the perirenal and scapular fat depots by 40 an 24%, respectively (P < .001)< and the body fat content by 28% (P < .01). There were no differences in the utilization of animal and vegetable fats, and only for some traits ADG, feed intake, kidney weights) did the diets with soybean oil result in better responses than those with oleins. The results indicate that fat addition to fibrous diets extends the rabbit's growing period without impairing the feed:gain ratio. The joints of rabbits killed at heavier weights have more desirable weights for marketing the carcass on a retail cut basis.

No abstract

No abstract

Two gas chromatography (GC) procedures were compared for routine analysis of trans fatty acids (TFA) of vegetable margarines, one direct with a 100-m high-polarity column and the other using argentation thin-layer chromatography and GC. There was no difference (P > 0.05) in the total trans 18:1 percentage of margarines with a medium level of TFA (~18%) made using either of the procedures. Both methods offer good repeatability for determination of total trans 18:1 percentage. The recoveries of total trans isomers of 18:1 were not influenced (P > 0.1) by the method used. Fatty acid composition of 12 Spanish margarines was determined by the direct GC method. The total contents of trans isomers of oleic, linoleic, and linolenic acids ranged from 0.15 to 20.21, from 0.24 to 0.99, and from 0 to 0.47%, respectively, and the mean values were 8.18, 0.49, and 0.21%. The mean values for the ratios [cis-polyunsaturated/(saturated + TFA)] and [(cis-polyunsaturated + cis-monounsaturated)/(saturated + TFA)] were 1.25 ± 0.39 and 1.92 ± 0.43, respectively. Taking into account the annual per capita consumption of vegetable margarine, the mean fat content of the margarines (63.5%), and the mean total TFA content (8.87%), the daily per capita consumption of TFA from vegetable margarines by Spaniards was estimated at about 0.2 g/person/d.Paper no. J9141 in JAOCS 77, 131-136 (February 2000).

Four diets were formulated to study the effect of a progressive substitution of grape pomace (GP) for alfalfa hay (AH) at the rates 0, 100, 200 and 300 g/kg total weight. The control diet contained 500 g AH and 192 g aciddetergent fibre per kg dry matter (DM). In experiment 1, 32 Californian XNew Zealand White rabbits were used to determine dietary nutrient apparent digestibility. The inclusion of GP decreased the apparent digestibility of crude protein (P < 0-001) and energy (P < 0-05). However, the digestible energy (DE) contents of the diets were similar because GP had a greater gross energy content than AH. In experiment 2, 36 rabbits given the same diets as in experiment 1 were used to determine several digestive and productive traits and chemical body composition (at 20kg live weight). Dietary inclusion of GP linearly decreased ammonia (P < 0-01), total volatile fatty acid concentration (P < 0-001) and the molar proportion of acetate (P < 0-05) in the caecum. Starch content in the Heal and caecal contents was low but linearly increased (P < 0-05) with increasing dietary concentration of GP. The average daily gain (from weaning at 30 days of age to 2-0 kg live weight) was not significantly affected (P > 0-10) by the diet, but the ratio gain -.food linearly decreased (P < 0-001) with the GP inclusion. Dietary inclusion ofGP linearly increased (P < 0-10) the fat content of the empty body of the rabbits. The efficiency of utilization of dietary DE and protein for growth were calculated by the comparative slaughter method, using the chemical body composition data of 22 suckling rabbits slaughtered at 30 days of age for the initial body composition. The efficiency of utilization of DE was not influenced by dietary GP inclusion, but GP linearly increased (P < 0-01) digestible crude protein utilization. The decrease in crude protein apparent digestibility may be the main reason that gain :food ratio was impaired in diets containing GP substituted for AH.