Effect of low moisture feed lick supplementation on rumen metabolism in sheep

Abstract

The quality and availability of forage varies over the grazing season and at times is nutritionally limiting. Low moisture feed licks (LMFLs) are a commercial supplement retailed as forage balancers that provide additional energy, protein, vitamins and minerals to the diet. Previous research has demonstrated that cattle consuming forage-based diets supplemented with LMFLs have increased voluntary forage intakes, increased digestibility and positive effects on animal performance. The aim of this thesis was to gain a deeper understanding of the biological basis underpinning the effect of LMFL supplementation on metabolism in sheep through a series of in-vitro, in-sacco and in-vivo studies to better explain effects in animal performance. The effect of LMFL supplementation on the performance of commercial breeding ewes in the uplands was measured. This study confirmed the potential of LMFLs to have a positive effect on ewe live
weight and reproductive performance. The effect of LMFL supplementation on rumen function, metabolism and aspects of the rumen microbiome of mature non-productive sheep were measured. LMFL supplementation had no effect on the dry matter degradation of forage in-vitro or in-sacco, the organic matter, neutral detergent fiber, acid detergent fiber or nitrogen total tract digestibility or voluntary forage intakes. LMFLs had a positive effect on rumen fermentation in-vitro with elevated gas production and molar concentrations of the major volatile fatty acids, acetate, butyrate and propionate. However similar observations were not made in-vivo. In whole animal trials preconditioning the rumen to LMFLs had no effect on the dry matter degradation of forage or rumen fermentation. LMFL supplementation had no effect on the microbial biomass of bacteria, methanogens, or anaerobic fungi recovered from the total solid (SAP) or liquid associated populations. LMFL supplementation and pre-conditioning the rumen to the LMFL had little effect on the structure, diversity or predicted functionality associated with carbohydrate and protein metabolism of the total or potential metabolically active bacterial SAP. In conclusion, LMFL supplementation has the potential to improve the performance of production animals. However, supplementation does not affect the degradation of forage, voluntary forage intake or rumen microbiota of mature non-productive animals. However, the supplement appeared to be utilised as a substrate for fermentation by rumen microbiota where increases in rumen fermentation products was observed. While the results were limited in these mature animals, the results indicate the potential for greater benefit to be gained from livestock at physiologically demanding times or when actively growing. Hence, further research is required to determine the effect of LMFL supplementation on the metabolism and rumen microbiome of production animals

Date of Award	2020
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Alison Kingston-Smith (Supervisor)