The dietary cation–anion difference (DCAD) has been receiving increased attention in recent years; however, information on rumen fermentation, cellulolytic bacteria populations, and microbiota of female goats fed a negative DCAD diet is less. This study aimed to evaluate the feasibility of feeding a negative DCAD diet for goats with emphasis on rumen fermentation parameters, cellulolytic bacteria populations, and microbiota. Eighteen female goats were randomly blocked to 3 treatments of 6 replicates with 1 goat per replicate. Animals were fed diets with varying DCAD levels at +338 (high DCAD; HD), +152 (control; CON), and −181 (low DCAD; LD). This study lasted 45 days with a 30-d adaption and 15-d trial period. The results showed that the different DCAD levels did not affect the rumen fermentation parameters including pH, buffering capability, acetic acid, propionic acid, butyric acid, sum of acetic acid, propionic acid, and butyric acid, or the ratio of acetic acid/propionic acid (p > 0.05). The 4 main ruminal cellulolytic bacteria populations containing Fibrobacter succinogenes, Ruminococcus flavefaciens, Butyrivibrio fibrisolvens, and Ruminococcus albus did not differ from DCAD treatments (p > 0.05). There was no difference in bacterial richness and diversity indicated by the indices Chao, Abundance Coverage-based Estimator (Ace), or Simpson and Shannon, respectively (p > 0.05), among 3 DCAD levels. Both principal coordinate analysis (PCoA) weighted UniFrac distance and unweighted UniFrac distance showed no difference in the composition of rumen microbiota for CON, HD, and LD (p > 0.05). At the phylum level, Bacteroidetes was the predominant phylum followed by Firmicutes, Synergistetes, Proteobacteria, Spirochaetae, and Tenericutes, and they showed no difference (p > 0.05) in relative abundances except for Firmicutes, which was higher in HD and LD compared to CON (p < 0.05). At the genus level, the relative abundances of 11 genera were not affected by DCAD treatments (p > 0.05). The level of DCAD had no effect (p > 0.05) on growth performance (p > 0.05). Urine pH in LD was lower than HD and CON (p < 0.05). Goats fed LD had higher plasma calcium over HD and CON (p < 0.05). In summary, we conclude that feeding a negative DCAD has no deleterious effects on rumen fermentation and rumen microbiota and can increase the blood calcium level, and is therefore feasible for female goats.

Background: Dietary cation–anion difference (DCAD) has been receiving increased attention in recent years; however, information on the rumen fermentation, cellulolytic bacteria populations, and microbiota of goats fed a low-DCAD diet is less. This study aimed to evaluate the feasibility of feeding a low-DCAD diet for goats with emphasis on rumen fermentation parameters, cellulolytic bacteria populations and microbiota. Growth performance, urine pH, and plasma metabolites were also analyzed as well. Materials and method: Eighteen goats were randomly allocated to 3 treatments with six replicates of each treatment and 1 goat per replicate. Animals were fed diets with varying DCAD levels at +338 (High DCAD; HD), +152 (Control; CON), and −181 (Low DCAD; LD). This study includes 15-d experimental period and 30-d adaption period. Results: The DCAD level did not affect the rumen fermentation parameters including pH, buffering capability, acetic acid, propionic acid, butyric acid, total volatile fatty acids, and ratio of acetic acid/propionic acid (P > 0.05). The 4 main ruminal cellulolytic bacteria populations including Fibrobacter succinogenes, Ruminococcus flavefaciens, Butyrivibrio fibrisolvens and Ruminococcus albus did not differ from DCAD treatments (P > 0.05). The DCAD levels did not affect bacterial richness and diversity indicated by the indices Chao, Ace and Simpson and Shannon, respectively (P > 0.05). Both weighted UniFrac and unweighted UniFrac showed no difference in the composition of rumen microbiota for CON, HD and LD (P > 0.05). At the phylum level, Bacteroidetes was the predominant phylum followed by Firmicutes, Synergistetes, Proteobacteria, Spirochaetae, and Tenericutes, and they showed no difference (P > 0.05) in relative abundances except for Firmicutes, which was higher in HD and LD compared to CON (P < 0.05). At the genus level, relative abundance of 11 genera were not affected by DCAD treatments (P > 0.05). Level of DCAD had no effect (P > 0.05) on growth performance including dry matter intake, average net gain, average daily gain, and feed conversion ratio; and nutrients digestibility of crude protein, neutral detergent fiber, acid detergent fiber, and organic matter (P > 0.05). Urine pH in LD was lower than HD and CON (P < 0.05). LD resulted in higher plasma calcium than HD and CON (P < 0.05) but not for other plasma metabolites (P > 0.05). Conclusion: We conclude that, with regard to the great importance of rumen fermentation, these results suggest that reducing DCAD is unharmful for rumen status and provide the feasibility of feeding a low-DCAD to goats.