Effects of lucerne particle size and source of dietary carbohydrates on in situ degradation and ruminal variables in sheep

Abstract

ABSTRACT:The effects of altering forage particle size and source of rapidly degradable carbohydrates on in situ degradation and ruminal variables were studied in four Iranian male sheep. The study was designed as a Latin square with a 2 × 2 factorial arrangement of treatments including two carbohydrate sources (pelleted beet pulp vs. maize-and barley-based concentrate) and two lucerne particle sizes (2.38 vs. 0.94 mm). Kinetics of disappearance of lucerne, concentrates and mixed samples was studied in situ. Among feed samples, the degradation rate constant of lucerne dry matter was higher (P < 0.02) and disappearance of lucerne neutral detergent fibre (NDF) in 4 h of incubation was lower (P = 0.06) in diets with reduced particle size. The rapidly degradable fraction of lucerne samples was also affected by treatments. Other degradability components were not affected. The mean ruminal pH was lower in diets containing short hay than in those containing long hay (5.76 vs. 5.86, P < 0.006) and pH values were consistently lower immediately after feeding diets with short lucerne hay. The form of carbohydrates did not affect ruminal pH, however, altering the source of carbohydrates changed the pattern of pH over time. Total volatile fatty acid (VFA) concentration and proportions of individual VFA were similar but numerical differences indicated a lower acetate to propionate ratio in diets with short hay. Most of the affected variables were influenced by the particle size of forage to a larger extent than by the source of rapidly degradable carbohydrates or the interaction between them. So, when sheep diets contain no more than 250 g/kg starch, the source of dietary carbohydrates may not interact with forage particle size to affect DM degradability and ruminal fermentation.

Effect of the type of non-fibre carbohydrates in grass silage-based diets on in sacco ruminal degradability and protein value of lupin (Lupinus angustifolius L. cv. Sonet) seeds ground to different particle sizes

“…Similarly, a reduction of susceptibility to digestion of lucerne hay NDF as the eff ect of dietary sucrose supplementation was observed in continuous culture fermenters by Ribeiro et al (2005). Th e infl uence of the type of non-fi bre carbohydrates included in the rations on the course of NDF degradation was reported by Alamouti et al (2009), who found out that the degradation of lucerne NDF in the early hours post feeding in sheep was aff ected by a signifi cant increase in rumen pH as a result of partial replacement of pectin by starch in the diets.…”

Pelleted Field Grass to Increases the Java Thin Tail Sheep Productivity

“…Decreasing of IVoDMD and IVoOMD (Table 2) in T1, due to increasing of feed particle rate of passage, expecially occur on slowly fermented DM component, namely CF (Banerjee, 1978). In in situ experiment on Iranian sheeps by Alamouti et al (2009) also showed that the degradability variables of ration was more depending on roughages/forages portion rather than RAC.Those caused molar proportion of acetic acid in T1 was lower than T2 (P<0.05). Decreasing of CF content and increasing of NFE content in consumed T2 ration, along with rice bran feeding, supposed caused the lower (P<0.05) molar proportion of acetic acid in T0 and T1 treatment groups (Flachowsky et al, 2006).…”

In situ and in vitro methods used to evaluate food and diets of ruminants

“…Tem-se verificado a ocorrência de aumento da taxa de digestão em decorrência da redução das frações do tamanho de partícula (Robles et al, 1980), podendo-se inferir que o aumento da exposição das frações digestivas ao ataque microbiano, devido a moagem, foi responsável por taxas de degradação mais rápidas. Alamouti et al (2009) observaram que a redução do tamanho de partículas na dieta de ovinos afetou significativamente a cinética de degradação de forragem, mas não de concentrados e dietas mistas. Da mesma forma, Casali et al (2008) verificaram um efeito mais pronunciado do tamanho de partícula, sobre as frações indigestíveis de alimentos e fezes bovinas, nos alimentos fibrosos em comparação aos alimentos concentrados e às fezes.…”