Pellets Inoculated with Bacillus amyloliquefaciens H57 Modulates Diet Preference and Rumen Factors Associated with Appetite Regulation in Steers

Simple Summary

The probiotic Bacillus amyloliquefaciens strain H57 (H57) may reinforce preferential feeding behaviour by changing ruminal fermentation parameters. Four rumen-fistulated steers were offered feedlot pellets, with (H57) or without (Control, C) the H57 probiotic. Half of the pellets were added to the rumen, at time zero, and half were offered for oral consumption over the next six hours, to make four feeding treatments. Each steer was offered each treatment over time. Each offering was over six days, with rumen fluid sampled over the last three days for a six-hour period per day. A five-minute preference test was performed at the end of each rumen sampling period by simultaneously offering the steers 4 kg of H57 and C pellets. The steers preferred the H57 over the C pellets but the route of offering (rumen versus oral) had no effect on preference. Ruminal pH and molar proportions of iso-butyrate and iso-valerate were higher and ammonia concentrations tended to be greater for H57 compared to C. However, since the route of offering had no effect on preference, the hypothesis, that ruminal fermentation changes take precedence over oral (taste) sensations in driving preference, was not supported.

Abstract

This study examined whether the probiotic Bacillus amyloliquefaciens strain H57 (H57) affects ruminal fermentation parameters that exercise post-ingestive feedback appetite control mechanisms. A 4 × 4 Latin square design was used to separate pre- and post-ingestive effects of H57 in four rumen-fistulated steers. The steers were offered a set amount of feedlot pellets, inoculated with H57 or without H57 (control, C). Half of the total amount of pellets fed were introduced intra-ruminally (r), and then the remaining pellets were orally consumed (o) to make four feeding treatments: H57r/H57o, H57r/Co, Cr/H57o and Cr/Co. Rumen fluid was sampled at 2, 4 and 6 h after feeding. Preference behaviour was tested immediately after the 6 h rumen fluid sampling by simultaneously offering the steers 4 kg of each of H57 and C pellets in adjacent troughs for 5 min. Steers preferred the pellets with added H57 over the C pellets (56:44; p < 0.001) and their preferences were not affected by the treatment protocol imposed to separate post- from pre-ingestive effects (p > 0.05). Steers fed H57 pellets had higher ruminal pH, molar proportions of iso-butyrate and iso-valerate (p < 0.05) and tended to have greater ruminal ammonia concentrations compared to those fed C pellets (p < 0.1). However, post-ingestive signals did not affect diet preference more than pre-ingestive signals.

Genomic diversity and breed composition of Vietnamese smallholder dairy cows

Vietnamese smallholder dairy cows (VDC) are the result of crossbreeding between different zebu (ZEB) and taurine dairy breeds through many undefined generations. Thus, the predominant breed composition of VDC is currently unknown. This study aimed to evaluate the level of genetic diversity and breed composition of VDC. The SNP data of 344 animals from 32 farms located across four dairy regions of Vietnam were collected and merged with genomic reference data, which included three ZEB breeds: Red Sindhi, Sahiwal and Brahman, three taurine breeds: Holstein (HOL), Jersey (JER) and Brown Swiss (BSW), and a composite breed: Chinese Yellow cattle. Diversity and admixture analyses were applied to the merged data set. The VDC were not excessively inbred, as indicated by very low inbreeding coefficients (Wright's F_IS ranged from -0.017 to 0.003). The genetic fractions in the test herds suggested that the VDC are primarily composed of HOL (85.0%); however, JER (6.0%), BSW 5.3%) and ZEB (4.5%) had also contributed. Furthermore, major genotype groupings in the test herds were pure HOL (48%), B3:15/16HOL_1/16ZEB (22%) and B2:7/8HOL_1/8ZEB (12%). The genetic makeup of the VDC is mainly components of various dairy breeds but also has a small percentage of ZEB; thus, the VDC could be a good genetic base for selecting high milk-producing cows with some degree of adaptation to tropical conditions.

Issues of Feeding Strategy for Lactating Cows in Vietnamese Smallholder Dairy Farms

A limited literature suggests relatively simple feeding regimes and diet formulation strategies for dairy cows in Vietnamese smallholder dairy farms (SDFs). This study aimed to classify and compare feeding regimes and nutrient balance for lactating cows between four typical dairy regions (south lowland, south highland, north lowland, and north highland) in Vietnam and evaluate the possibility of systematic dietary imbalance. Eight SDFs from each of the four regions were visited for two adjacent milking periods per farm. For each visit, frequency and methods of feed and water supply to the lactating cows were recorded, and individual fat corrected milk yield (ECM) of lactating cows were calculated from milk yield and fat concentration. The amount of each diet ingredient offered and refused by each lactating group was weighed and sampled for calculation of dry matter intake per cow (DMI) and analysis of nutrient composition in the component offered. PCDairy, a diet formulation computer model, was used to calculate actual and recommended dietary nutrient concentrations and predict potential milk production. Factor analysis, cluster analysis, and ANOVA were applied to determine grouping effects across as well as between regions. Feeding regimes and diets were grouped into three and nine clusters, respectively. Farmers in the same region tended to apply similar diets and feeding regimes. Across regions, only 47% of all SDFs supplied water ad libitum to the cows. The most used roughages including Napier grass, corn silage, fresh corn with cob, and rice straw were all relatively high in neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL). The diets in all regions were excessive in crude protein, NDF, ADF, ADL, and most minerals (Ca, P, Mg, K, Na, S, Fe, Zn, Cu, and Mn) but insufficient in net energy and non-fibre carbohydrate. Feed efficiency (1.06 kg FCM/kg DMI) of the diets were sub-optimal. Feeding regimes and dietary nutrient balance of the south lowland SDFs were most problematic. Increasing dietary net energy concentration by increasing the use of starch and fat and decreasing dietary fibre concentration by decreasing the use of Napier grass or rice straw to balance the diets might help improve the milk production and thereby increase feed efficiency.

Assessment of Performance and Some Welfare Indicators of Cows in Vietnamese Smallholder Dairy Farms

Smallholder dairy farms (SDFs) are distributed widely across lowland and highland regions in Vietnam, but data on the productivity and welfare status of these cows remains limited. This cross-sectional study was conducted to describe and compare the productivity and welfare status of SDF cows across contrasting regions. It was conducted in autumn 2017 on 32 SDFs randomly selected from four typical but contrasting dairy regions (eight SDFs per region); a south lowland, a south highland, a north lowland, and a north highland region. Each farm was visited over a 24-h period (an afternoon followed by a morning milking and adjacent husbandry activities) to collect data of individual lactating cows (n = 345) and dry cows (n = 123), which included: milk yield and concentrations, body weight (BW), body condition score (BCS, 5-point scale, 5 = very fat), inseminations per conception, and level of heat stress experienced (panting score, 4.5-point scale, 0 = no stress). The high level of heat stress (96% of lactating cows were moderate to highly heat-stressed in the afternoon), low energy corrected milk yield (15.7 kg/cow/d), low percentage of lactating cows (37.3% herd), low BW (498 and 521 kg in lactating and dry cows, respectively), and low BCS of lactating cows (2.8) were the most important productivity and welfare concerns determined and these were most serious in the south lowland. By contrast, cows in the north lowland, a relatively hot but new dairying region, performed similarly to those in the south highland; a region historically considered to be one of the most suitable for dairy cows in Vietnam due to its cool environment. This indicates the potential to mitigate heat stress through new husbandry strategies. Cows in the north highland had the highest BW (535 and 569 kg in lactating and dry cows, respectively) and the highest energy corrected milk yield (19.2 kg/cow/d). Cows in all regions were heat-stressed during the daytime, although less so in the highlands compared to the lowlands. Opportunities for research into improving the productivity and welfare of Vietnamese SDF cows are discussed.

Feed Preference Response of Weaner Bull Calves to Bacillus amyloliquefaciens H57 Probiotic and Associated Volatile Organic Compounds in High Concentrate Feed Pellets

Simple Summary

The aim of this work was to confirm that a new probiotic (Bacillus amyloliquefaciens, H57) in stock-feed pellets make cattle want to eat them faster and that H57 increased preference by reducing the rate of microbial spoilage in stored pellets thereby changing the odour of the pellets. Odour was manipulated by manufacturing standard pellets with or without added H57 and then storing half of each for 4 months either in a chiller or at room temperature to make 4 different batches. These were offered, per day for 4 weeks, across 8 automated feed bunks, 1 pellet batch per 2 bunks, in amounts enough to satisfy the daily needs of a single group of 16 young bulls. A given bull could have chosen any of 4 feed batches to eat. The feed batches in the bunks that were emptied the fastest were considered to contain the most preferred batch. The H57 was found to improve preference for pellets but only when they were stored at room temperature and not if they were stored in a chiller. The most preferred pellets had the least concentration of microbial volatile organic compounds. This was consistent with our expectation that H57 inhibits microbial spoilage in feed pellets to improve shelf life.

Abstract

This study tested the hypothesis that Bacillus amyloliquefaciens strain H57 (H57) improves preference by reducing the development of microbial volatile organic compounds (mVOCs) in feed pellets. Sixteen bull calves were, for 4 weeks, provided equal access to a panel of 8 automated feed bunks in a single paddock with some hay. Each bunk contained pellets with (H57) or without (Control) the H57, each aged for 4 months at either ambient or chiller temperature. Each treatment was changed to a new bunk pair position weekly. Relative preference was determined according to weight of pellets remaining per hour per treatment bunk pair per 24 h. Pellets were analysed for volatile organic compounds (VOCs) and the concentrations tested for correlation with relative preference. Calves showed the lowest preference (p < 0.0001) for the Control/Ambient treatment whereas preference for all other treatments (H57/Ambient; H57/Chiller; Control/Chiller) was similar. The Control/Ambient treatment odour profile grouped differently to the other 3 treatments which grouped similarly to each other. Up to 16 mVOCs were determined to have potential as pre-ingestive signals for the extent of microbial spoilage. Further studies are required to find which combination of these mVOCs, when added to pellets, results in feed aversion.