Effects of primary growth compared to regrowth grass silage on feed intake, growth performance and carcass traits of growing bulls

Arto Kalevi Huuskonen,Maiju Pesonen,Sari Rämö

doi:10.23986/afsci.74582

Arto Kalevi Huuskonen, Maiju Pesonen + Show 1 more

Open Access

https://doi.org/10.23986/afsci.74582

Copy DOI

Abstract

The objective was to study the effects of primary growth vs. regrowth grass silage on intake, growth and carcass traits of growing bulls. In a feeding experiment, 30 bulls were offered a total mixed ration ad libitum. Two dietary treatments included either first or second cut grass silage (550 g kg-1 dry matter) supplemented with rolled barley (435 g kg-1 dry matter) and a mineral-vitamin mixture (15 g kg-1 dry matter). Feed and energy intake as well as the live weight gain of the bulls decreased when the second cut silage was used instead of the first cut silage. No differences in carcass conformation or carcass fat score between the treatments were observed. Analysed chemical, digestibility or fermentation parameters of the silage samples did not explain the differences in feed intake. However, some second cut silage samples were found to contain mycotoxins (zearalenone, roquefortine C, mycophenolic acid and HT-2), but it is difficult to estimate whether this was the factor that affected feed intake in the present study.

Highlights

Grass silage is the main forage offered to growing cattle in the Nordic countries
Peoples and Gordon (1989) and Heikkilä et al (1998) concluded that the lower milk production potential of autumn silages compared to spring silages was due to reduced silage DM intake (DMI) even though there were no differences between the digestibilities of the spring and autumn silages
The second cut silage had a 7% higher SDMI index compared to the first cut silage

Summary

Introduction

In Finland, two or three cuts are usually harvested from swards during the grass growing period and the digestibility is typically lower for regrowth grass compared with primary growth grass (Kuoppala 2010). The importance of grass silage digestibility for growing cattle is demonstrated in several studies Based on a meta-analysis, Huuskonen et al (2013a) observed that a 1 g kg-1 dry matter (DM) increase in digestible organic matter (DOM) in DM (D-value) increased grass silage DM intake (DMI). In dairy cows, Kuoppala et al (2008) observed a lower DMI of regrowth grass silage compared to late harvested primary growth silage, most of the chemical and digestibility parameters were similar and the only marked difference was the higher neutral detergent fibre (NDF) concentration of primary growth silage. In finishing Simmental bulls, Huuskonen and Pesonen (2017)

Methods

Results

Conclusion