Work

Impact of dietary forage proportion and crossbreeding on feed efficiency and methane emissions in lactating dairy cows

Year: 2024

Type: article

Abstract: Increasing forage proportion (FP) in the diets of dairy cows would reduce competition for human edible foods and reduce feed costs, particularly in low-input systems. However, increasing FP reduces productivity and may increases methane (CH 4 ) emission parameters. This work aimed to investigate the impact of FP and breed on feed efficiency and CH 4 emission parameters. Data from 32 individual experiments conducted at the Agri-Food and Biosciences Institute between 1992 and 2010 were utilised in this study resulting in data from 796 Holstein-Friesian (HF), 50 Norwegian Red (NR), 46 Jersey × HF (J × HF) and 16 NR × HF cows. Diets consisted of varying proportions of forage and concentrate dependent on the experimental protocols of each experiment. A linear mixed model was used to investigate the effect of low (LFP; 10% to 30%), medium (MFP; 30% to 59%), high (HFP; 60% to 87%) and pure (FOR; 100%) FP (dry matter [DM] basis) and breed on feed efficiency, and CH 4 emission parameters and multivariate redundancy analysis identified associations between animal and dietary drivers on the same variables. Total dry matter intake (DMI) was higher for cows offered LFP (17.3 kg/d) and MFP (17.9 kg/d) compared to HFP (15.3 kg/d) and FOR (13.8 kg/d) ( P < 0.001). Milk yield ( P < 0.001), milk yield/DMI ( P < 0.001), energy corrected milk (ECM)/DMI ( P < 0.001) and milk energy/DMI ( P < 0.001) were higher for LFP and MFP compared to HFP and FOR. Methane/DMI was higher for HFP (24.3 g/kg) compared to MFP (22.4 g/kg) ( P < 0.001). Methane/milk yield ( P < 0.001) or CH 4 /ECM ( P < 0.001) was higher for HFP (22.5 or 21.6 g/kg) and FOR (27.0 or 25.8 g/kg) compared to MFP (19.1 or 17.9 g/kg). There were no differences between LFP and MFP or between HFP and FOR for milk yield, milk yield/DMI, ECM/DMI, milk energy/DMI, CH 4 /milk yield and CH 4 /ECM ( P > 0.05). Differences existed between breeds for residual feed intake ( P = 0.040), milk yield/DMI ( P = 0.041) and CH 4 /DMI ( P = 0.048) with multivariate redundancy analysis demonstrating negative correlations with efficiency and positive correlations with CH 4 /DMI and CH 4 /milk yield. Feeding concentrates at 70% to 90% of DMI (LFP group) would not result in any further benefits for productivity, feed efficiency or CH 4 yield and intensity when compared to feeding 41% to 70% concentrates of DMI (MFP group). There may be opportunity to improve profitability for lower intensity farms with less concentrate input.

Source: Animal nutrition

DOI: 10.1016/j.aninu.2024.08.011