Effect of diet quality on dry matter intake, gene expression, greenhouse gas emissions, and production measures in mature beef cows

Abstract

The purpose of this research was to examine the effect that diet quality had on dry matter intake, gene expression, greenhouse gas emissions, and production measures in gestating, mature Angus beef cows. Two experiments were conducted in consecutive years using a total of 90 gestating, non-lactating cows. In each trial, cows were assigned to one of two diet sequences, concentrate-forage (CF) or forage-concentrate (FC), so that age, body weight, body condition score, and days pregnant were equal across sequence. The diet sequence refers to the order in which two diets, a forage-only diet (HAY) and a concentrate-based diet (MIX) were consumed during two intake periods. In the first study, skeletal muscle from the semitendinosus muscle was collected at initiation, midpoint, and termination of the study and examination of the transcriptome through RNA-sequencing used to identify differentially expressed genes associated with diet quality and with intake classification (high or low intake). In total, 259 differentially expressed genes were associated with diet quality. In the second study, greenhouse gas emissions data was collected using a GreenFeed Emissions Monitoring (GEM) system to evaluate the effect of diet quality and diet sequence on gas emissions. During the first intake period, gas emissions were significantly associated with dry matter intake regardless of diet or sequence, highlighting the viability of using gas emissions data as a proxy for collection of intake data on both a forage diet and a concentrate-based diet.