Ruminant animals obtain their energy for production through ruminal fermentation. Nutritionists have long been in search for additives to increase rumen degradability through the alteration of the rumen microbiome. Probiotics have been researched not only for the health benefit that they hold, but for increasing production performance by altering the rumen microbiome to increase degradation, leading to more nutrients available for absorption. Probiotics are known to stabilise rumen pH and thereby creating an optimal environment for cellulolytic bacteria to function and thus increase the degradation of fibre in the rumen. The objective of the current study was to determine if a multi-strain bacterial probiotic (MSBP; 8 × 109 CFU), containing Bacillus, Lactobacillus and Bifidobacterium species can increase dry matter intake (DMI) and growth performance while decreasing feed conversion ratio (FCR) as well as deliver a desirable carcass composition of feedlot lambs. The effect of this MSBP was investigated within two trials, including an in vivo feedlot sheep trial and an in vitro gas production study.
The in vivo trial assessed the production performance of Dohne Merino feedlot lambs receiving three levels of MSBP inclusion, including low inclusion (LI) level equivalent to 250 g MSBP/ton feed (as is), medium inclusion (MI) level equivalent to 500 g MSBP/ton feed (as is) and high inclusion (HI) level equivalent to 750 g MSBP/ton feed (as is), compared to a control group. The addition of MSBP had no effect on DMI, total weight gain, average daily gain (ADG), FCR, dressing percentage or carcass classification. The inclusion of MSBP in the adaptation period resulted in increased weight gain for LI and MI treatment groups (P ≤ 0.05), while the control group managed to lose weight during this period. Results demonstrate that MSBP supplementation has no effect on growth parameters, except the adaptability to the feedlot diet.
The in vitro gas production study was conducted to determine if MSBP inclusion have the ability to increase the rate and extent of rumen degradability. Rumen fluid from cannulated Holstein dairy cows were used as inoculum to incubate three MSBP inclusion levels compared to a control. The inclusion rates in the in vitro study were equivalent to in vivo inclusion rates. With each treatment replicated six times, kinetic parameters were derived from a non-linear model. No difference in total gas production was observed for LI and MI, compared to the control group. Compared to the control, the addition of MSBP increased the total gas production (P < 0.001) for the HI treatment group. The addition of MSBP had no effect on gas production rate or lag time between four different treatment groups. Results demonstrate that this MSBP might be dose dependent as an increase in extent of degradation was observed at the highest MSBP inclusion rate. It was concluded that MSBP increase ruminal fermentation and can increase the number of nutrients available for absorption.