Effects of carbohydrates from citrus pulp and hominy feed on microbial fermentation in continuous culture.

Abstract

Eight dual-flow continuous-culture fermenters were used to evaluate the effect of neutral detergent-soluble carbohydrates (NDSC) on fermentation by ruminal microorganisms. Citrus pulp and hominy feed were added to a basal diet as sources of NDSC, with citrus pulp providing neutral detergent-soluble fiber (NDSF) in the form of pectic substances and with hominy feed in the form of starch. The basal diet contained 26.7% corn silage, 6.0% alfalfa hay and 3.8% cottonseed hulls on a DM basis. The dried citrus pulp diet contained on a DM basis 17.2% CP, 34.7% NDF, 33.7% NDSC, and 14.4% NDSF, whereas the hominy feed diet contained 17.9% CP, 33.2% NDF, 35.9% NDSC, and 8.8% NDSF. Organic matter, DM, and NDF and ADF digestion were not affected by source of carbohydrate. Ammonia N concentration was greater (P < 0.05) for the hominy feed diet (14.2 mg/100 mL) than for the dried citrus pulp diet (9.3 mg/100 mL). Total N, nonammonia N, microbial N, and dietary N flows were not affected by treatments; however, the efficiency of microbial protein synthesis was greater (P = 0.055) for the dried citrus pulp diet than for the hominy feed diet (30.6 vs 27.8 g of bacterial N/kg of OM truly digested). Results from this experiment indicate that NDSF from citrus pulp can provide similar sources of energy compared with starch from hominy feed to support ruminal microbial growth.

Effects of dietary energy and nitrogen supplements on rumen fermentation and protozoa population in buffalo and zebu cattle

“…The differences obtained in the average values for volatile fatty acids production in the rumen of buffaloes and zebu cattle fed two energy and two nitrogen sources (Table 2) did not support the findings of Ariza et al (2001) with in vitro study, which indicated a similar effect of citrus pulp and hominy for rumen microbial growth. Barrios-Urdaneta (2003) also observed no difference in the ruminal pH and volatile fatty acid production in the rumen of sheep fed ammonia-treated straw supplemented with different barley grain and citrus pulp ratios.…”

“…Citrus pulp has good potential for use in ruminant feeding systems as an energy source, in place of corn, since some experiments have suggested that citrus pulp may not depress ruminal pH as much as corn grain (Villarreal et al, 2006). However, Ariza et al (2001) observed with in vitro evaluation that neutral detergent-soluble fiber from citrus pulp can provide similar energy sources compared with starch from ground maize to support ruminal microbial growth.…”

Fibra solúvel e amido como fontes de carboidratos para terminação de novilhos em confinamento

“…Estas diferenças demonstraram que os carboidratos solúveis não podem ser estudados como um pool e que diversas interações devem ser esperadas entre os diferentes tipos de carboidratos solúveis e as fontes de proteína e as fontes e os teores de fibra, como observado por Ariza et al (2001), segundo os quais é possível alterar a fermentação ruminal com fontes alimentares de amido ou fibra solúvel. Estes autores verificaram maior eficiência na síntese de proteína microbiana e maior retenção do nitrogênio amoniacal quando utilizaram fibra solúvel em comparação a uma fonte de amido.…”

“…Em geral, os carboidratos solúveis são considerados um grupo de substâncias com características semelhantes. No entanto, diferentes fontes de carboidratos solúveis podem produzir diferentes padrões de fermentação ruminal (Hall, 2000;Ariza et al, 2001;Bomfim, 2003). Este grupo é muito heterogêneo e inclui ácidos orgânicos, açúcares (mono e oligossacarídeos), amido e frutanas, além dos carboidratos encontrados na parede celular das plantas, mas solúveis em detergente neutro, como a pectina, galactanos e β-glucanos.…”

“…Segundo Ariza et al (2001), é possível alterar a fermentação ruminal com fontes de amido ou de fibra solúvel em detergente neutro, sendo esperados aumento da eficiência de síntese de proteína microbiana ruminal e decréscimo na concentração de amônia quando fibra solúvel em detergente neutro é utilizada. Bomfim (2003) verificou que o balanceamento dos carboidratos solúveis em detergente neutro deve ser observado para cabras leiteiras, pois o aumento do teor de fibra solúvel em detergente neutro reduziu o conteúdo de proteína do leite.…”