Effect of replacing conventional feeds with tropical agricultural by-products on the growth performance, nutrient digestibility and ruminal microbiota of water buffaloes.

This study investigated the effect of replacing corn grain, soybean meal and wheat bran with tropical agricultural by-products, such as palm kernel cake (PKC), cassava residue and dried distiller's grain with solubles (DDGS), on the dry matter intake (DMI), growth performance, apparent nutrient digestibility, ruminal short-chain fatty acids (SCFA) and ruminal microbial communities of water buffaloes. Thirty healthy 15-month-old crossbred water buffaloes with a similar initial body weight of 353.1 ± 23.7 kg were randomly allocated into three dietary experimental groups, and they were fed with same forage but three different concentrates for 50 days fattening. The dietary treatments were as following: typical concentrate (TC, 65% corn + 15% wheat bran + 15% soybean meal), partial replacement concentrate Ⅰ (PRC I, 50% corn + 22.5% corn gluten + 22.5% PKC) and partial replacement concentrate Ⅱ (PRC II, 50% corn + 22.5% cassava residue + 22.5% DDGS). The results showed that the average daily gain of the PRC II group was the highest, and the DMI, acid detergent fibre digestibility and neutral detergent fibre digestibility value of the three groups were different and in the following order: PRC II group > TC group > PRC I group. The crude protein digestibility of PRC II was higher than that of the TC and PRC I groups (p < .05). The ruminal concentrations of total SCFA, acetate, propionate and butyrate of TC group were higher than the other two groups (p < .05). The PRC I group had the highest Bacteroidetes-to-Firmicutes ratio (B/F) and relative abundance of the genus Prevotella, while the PRC II group had the lowest B/F and relative abundance of Prevotella. In conclusion, using PKC and corn gluten to completely replace common feed ingredients in the buffalo concentrate ration decreased, while using cassava residue and DDGS increased animal growth performance, mainly due to the different combination influenced nutrient digestibility and ruminal microbial community composition was shifted.

Comparisons of Corn Stover Silages after Fresh- or Ripe-Corn Harvested: Effects on Digestibility and Rumen Fermentation in Growing Beef Cattle.

Both waxy corn stover after fresh- (CF) and ripe-corn (CR) harvested are important byproducts of corn cropping system and have 20 d difference in harvest time. The study aimed to investigate the effects of prolonging harvest time on the nutritive value of corn stover silage by comparing CF with CR silages. In vitro ruminal experiment was firstly performed to investigate substrate degradation and fermentation of CF and CR silages. The CR diet was formulated by replacing 50% forage of CF silage with CR silage on a dry matter (DM) basis. Fourteen crossbred steers (Simmental × Limousin × local Chinese) aged 13 months with an average weight of 318.1 ± 37.1 kg were selected and randomly allocated into two dietary treatment groups. Although the CR silage had greater DM and fiber contents than CF silage, it did not alter in vitro degradation (p > 0.05), but with lower molar percentage of propionate and acetate to propionate ratio (p < 0.05). The cattle fed CR diet had a higher DM intake and lower fiber digestibility with reduction in 18S rRNA gene copies of protozoa and fungi and 16S rRNA gene copies of Fibrobacter succinogenes (p < 0.05). Further 16S rRNA gene amplicon analysis indicated a similar diversity of bacteria community between CR and CF treatments (p > 0.05). Few differences were observed in the abundance of genera larger than 1% (p > 0.05), except for the reduction in abundance of genera Ruminococcaceae_NK4A214_group in CR treatment (p < 0.05). In summary, prolonging 20 d harvest time of corn stover silage increases the forage fiber and DM content, which promotes feed intake with decreased fiber degradation, although rumen fermentation and growth performance are not changed in growing beef cattle.

A comparative study on rumen ecology of water buffalo and cattle calves under similar feeding regime.

In all, 12 male water buffalo (Bubalus bubalis) calves and Holstein (Bos taurus) calves of similar age (10 ± 5 days) were selected to explore the mechanism underlying the differences in growth performance and feed conversion ratio between the two species. The experiment contains 33 days of sucking period and 40 days of post-weaning period. Both calves were fed the same amounts of milk in sucking period, and starter and oat grass were supplied ad libitum both before and after the weaning period. Feed intake, growth performance, ruminal fermentation parameters and the ruminal microbial community were measured the during experiment period. Results showed no differences in growth performance and feed intake between the two species in sucking period; however, the feed/gain ratio (F/G) of the water buffalo was higher than that of Holstein calve (p > 0.05). After weaning, the intake of starter by the Holstein calf was higher while intake of grass by the water buffalo was higher resulting in higher growth performance of and a lower F/G ratio for Holstein (p < 0.05). The rumen of Holstein calf showed higher levels of propionate, lower levels of acetate and branched-chain fatty acids than that of water buffalo during both periods (p < 0.05). The rumen of water buffalo showed a higher number of observed bacterial species and Shannon diversity as compared with that of Holstein calf. The members belonging to the bacterial phylum Bacteroides and genus Prevotella in the rumen of Holstein calf were higher (p < 0.05), while Firmicutes and fibrolytic bacteria Ruminobacter and Ruminococcus were lower (p < 0.05) than that of water buffalo. In conclusion, the water buffalo calves demonstrated clearly of having significant population of bacterial community and better fibre digestion than those of cattle calves.

Ruminal fermentation and microbial community differently influenced by four typical subtropical forages in vitro.

The present study evaluated the effects of 4 typical subtropical forages on ruminal microbial community composition to formulate a better diet for buffalo. Corn straw silage, elephant grass, cassava residues and sugarcane tail silage were used as substrates for in vitro fermentation. Eight replicates were set up for every substrate, and fermentation was carried out in a 100-mL glass syringe, using buffalo rumen inoculum. Every replicate was anaerobically dispensed with 10 mL of rumen inoculum, 20 mL of McDougall's buffer and 200 mg of dried substrate, and placed in a water bath at 39 °C. Gas production was recorded at 0, 2, 6, 12, 24, 36, 48 and 72 h of incubation. After 24 h, fermentation was ceased for 4 replicates and samples were collected. Volatile fatty acids (VFA) concentrations were measured using gas chromatography. Microbial populations were quantified using quantitative real-time PCR (qRT-PCR), and microbial community was analyzed using high throughput sequencing technology. The results showed, cassava residues as substrate had the highest gas production, acetate, propionate and total VFA concentrations (P < 0.05), and corn straw silage had the lowest acetate:propionate ratio (P < 0.05). The lowest numbers of fungi, Ruminococcus albus and Fibrobacter succinogenes, and the highest number of protozoa were observed with cassava residues (P < 0.05). The least abundances of bacterial phyla Firmicutes, Bacteroidetes and genus Prevotella, and substantially higher abundance of phylum proteobacteria (56%) and genus Succinivibrio (52%) were observed with cassava residues. The most abundances of Methanobrevibacter gottschalkii and Entodinium were observed with cassava residues. Spearman's correlations analysis showed, Succinivibrio had strong positive correlations with propionate, butyrate, Metadinium and M. gottschalkii, indicating fermentation products were related to microbial community. In conclusion, incubation with cassava residues resulted in lower number of fiber degrading microbes but higher protozoal population because of its low fiber contents. The microbial community was highly altered by in vitro incubation with cassava residues, whereas remained similar for the other 3 high fiber containing substrates.