Effect of dietary physically effective fiber on ruminal fermentation and the fatty acid profile of milk in dairy goats

Abstract

The objective of this experiment was to characterize the relationship among rumen fermentation variables, milk fatty acid profile, and dietary physically effective neutral detergent fiber (peNDF) content in a study that controlled for the potential confounding effects of dissimilar dry matter intake among treatments. Ten multiparous Xinong Saanen dairy goats were divided into 2 groups with 2 ruminally cannulated goats per group. Goats in each group were assigned to 1 of 2 dietary treatments (high and low peNDF) according to a 2×2 crossover design with 2 periods. The peNDF content of alfalfa hay (proportion of neutral detergent fiber retained on an 8.0-mm screen) was 42.1% for the high-peNDF and 14.5% for the low-peNDF group. To ensure similar dry matter intake, each morning the amount of alfalfa hay consumed on the prior day by the high-peNDF group was determined (amount offered minus morning refusals), and this was the amount of hay offered to the low-peNDF group that day. Each adaptation period consisted of 21d, followed by a 9-d sampling period. Dry matter intake and milk production and composition were similar between treatments. Milk energy efficiency increased with low dietary peNDF. Duration of pH below 5.60 was longer for goats fed the low-peNDF ration compared with the high-peNDF ration (4.08 vs. 0.41h/d); however, mean rumen pH (6.05 vs. 6.13) was not different between treatments. Reducing dietary peNDF increased rumen total volatile fatty acids (114.6 vs. 95.1mM) and decreased chewing time (404 vs. 673min/d), but did not affect the ratios of acetate, propionate, and butyrate. The relative abundance of Fibrobacter succinogenes and Ruminococcus flavefaciens increased with reduced dietary peNDF, but Ruminococcus albus proportions were not influenced by treatment. Reducing dietary peNDF decreased the proportion of iso C14:0, iso C15:0, and trans-11 C18:1 in milk fat, whereas the iso C17:0 and trans-10 C18:1 increased. This study demonstrated that low dietary peNDF in dairy goats increases rumen volatile fatty acids, reduces chewing time, and is correlated to the amount of F. succinogenes and R. flavefaciens.

Does the level of forage neutral detergent fiber affect the ruminal fermentation, digestibility and feeding behavior of goats fed cactus pear?

“…In this study, animals fed diets with the highest level of fNDF (463 g/kg DM) spent more time ruminating (+232 min) when compared to a level 0 g fNDF/kg DM. Increases of dietary fNDF levels decreased resting time, which was expected due to chewing activity being stimulated by forage sources (Li et al., ).…”

“…The increase in ruminal pH with the inclusion of fNDF levels could be attributed to high dietary fiber that stimulates chewing activity (Li et al., ), thus promoting an increase in the flow of saliva. Saliva production is very important for rumen function because it has a high buffering capacity as a result of a high concentration of bicarbonate and phosphate (Bailey & Balch, ).…”

“…Although there was an absence of effects on total VFA, it was possible to observe a decrease in the numerical values in total VFA from the inclusion of 339 g fNDF/kg DM in the diet. The high concentration of fNDF resulted in lower total VFA compared with diets with low concentrations of fNDF (Li et al., ). In this study, a high amount of cactus pear (622.0 and 475.8 g/kg on a DM basis) used in the diets with 0 and 109 g fNDF/kg DM, respectively, promoted an increased production of VFA due to these diets having the highest contents of NFC, which are fast‐degrading carbohydrates.…”

“…These characteristics and the low physically effective neutral detergent fiber (NDF) of cactus pear have resulted in metabolic disorders with diarrhea and weight loss when ruminant animals were fed cactus pear without any other forage source (Tegegne et al., ). In this context, the addition of NDF from other forage sources in diets containing cactus pear could increase the physically effective dietary fiber and promote rumination by stimulated chewing activity, which maintains the flow of saliva and ruminal pH buffering (Branco et al., ; Li et al., ).…”

Behavior of sheep fed babassu cake (Orbygnia speciosa) as a substitution for elephant grass silage

“…However, before adding a new roughage feed to the diet of ruminants, it is important to observe the effectiveness of the fiber, which is influenced by the NDF content and particle size; such characteristics are associated with the feed's ability to stimulate chewing and release through salivation substances that act as buffers in the maintenance of pH to ensure the development and action of microorganisms, thus ensuring proper rumen functioning (Li et al 2014).…”