Meta-analysis of the impact of stocking rate on the productivity of pasture-based milk production systems

Abstract

The objective of this study is to quantify the milk production response per cow and per hectare (ha) for an incremental stocking rate (SR) change, based on a meta-analysis of published research papers. Suitable experiments for inclusion in the database required a comparison of at least two SRs under the same experimental conditions in addition to details on experimental length and milk production results per cow and per ha. Each additional increased SR treatment was also described in terms of the relative milk production change per cow and per ha compared to the lower base SR (b_SR). A database containing 109 experiments of various lengths with 131 comparisons of SR was sub-divided into Type I experiments (common experimental lengths) and Type II experiments (variable experimental lengths). Actual and proportional changes in milk production according to SR change were analysed using linear mixed model procedures with study included as a random effect in the model. Low residual standard errors indicated a good precision of the predictive equations with the exception of proportional change in milk production per cow. For all milk yield variables analysed, the results illustrate that while production per cow is reduced, a strong positive relationship exists between SR and milk production per ha. An SR increase of one cow/ha resulted in a decrease in daily milk yield per cow of 7.4% and 8.7% for Type I and Type II data, respectively, whereas milk yield per ha increased by 20.1% and 19.6%, respectively. Within the Type II data set, a one cow/ha increase in SR also resulted in a 15.1% reduction in lactation length (equivalent to 42 days). The low predictability of proportional change in milk production per cow according to the classical SR definition of cows per ha over a defined period suggests that SR may be more appropriately defined in terms of the change in available feed offered per animal within each treatment.

Enteric methane output from selected herds of beef cattle raised under extensive arid rangelands

“…Animal production attributes such as milk production, body condition score and body weight are negatively Figure 1 Seasonal changes in daily (mean ± s.e) CH 4 concentration from the cows in different parities correlated with the increase in stocking rate (McCarthy et al 2014). Research indicated that an increase in stocking rate results in increased grazing intensity, which will subsequently result in lower daily herbage allowance (McCarthy et al 2011). Changes in seasons from wet to dry meant that available forage material is fibrous and is not palatable, hence lowering DMI.…”

Factors associated with the financial performance of spring-calving, pasture-based dairy farms

“…Furthermore, although milk production/cow is low, milk production/hectare can be high (Macdonald et al, 2008;McCarthy et al, 2011). Nonetheless, the low milk production per cow is often seen as a limitation that can be improved upon through improved genetics (Ramsbottom et al, 2012), reduced stocking rate (Macdonald et al, 2008;McCarthy et al, 2011), or the provision of additional feed as a supplement to pasture (Kennedy et al, 2002;Horan et al, 2004;Roche et al, 2006). There are well-defined response curves to these management changes and, in theory, it is possible to increase milk production/cow through changes in these variables and improve productivity and profitability.…”

The effect of stocking rate on soil solution nitrate concentrations beneath a free-draining dairy production system in Ireland

“…Similar to both Valentine et al (2009) andFariña et al (2011), SR had no significant effect on net herbage accumulation but, as a consequence of the increased efficiency of herbage removal and increased grazing severity at higher SR, resulted in increased grazed grass utilization. Both Baudracco et al (2010) and McCarthy et al (2011) have previously likened an increase in SR to a reduction in daily herbage allowance. In the current study, increasing SR resulted in reduced daily herbage allowance, reduced total lactation milk production per cow, and increased milk production per hectare, which is consistent with previous experiments at similar SR (Macdonald et al, 2008;Fariña et al, 2011).…”

“…By virtue of lower production costs, milk production from grass-based systems in Ireland and northwest Europe are anticipated to expand based on the production and utilization of increased quantities of high-quality grass (Lips and Reider, 2005;O'Donnell et al, 2008;DAFM, 2011). Stocking rate (SR; cows/ha), defined as the number of animals per unit area of land used during a specified period of time, is well accepted as the main driver of productivity within grazing systems (Hoden et al, 1991;Macdonald et al, 2008;McCarthy et al, 2011), and recent studies have highlighted the beneficial effects of a high SR on animal productivity, grazed grass utilization, and overall farm system efficiency (Kelly et al, 2012;McCarthy et al, 2013a). Notwithstanding these beneficial effects, previous studies have also indicated that where increased SR are associated with increased chemical fertilizer N application and off-farm supplementary feed importation, N surpluses increase and N utilization is reduced, resulting in increased N loss to ground water and the general environment (Di and Cameron, 2002a;Treacy et al, 2008;Ryan et al, 2011).…”