Pasture‐based dairy farm systems increasing milk production through stocking rate or milk yield per cow: pasture and animal responses

Abstract

A 2-year whole-farm study compared pasture-based systems increasing milk production per ha by increasing either stocking rate (from 2AE5 to 3AE8 cows ha )1 ) or milk yield per cow (from 6000 to 9000 kg cow )1 lactation )1 ) or both. Four treatments (systems), comprising 30 cows each, were compared under the same management and grazing decision rules. The diet was based on grazed pasture, whereas pellets and conserved fodder were fed when deemed necessary. Milk production per ha increased by 0AE49, 0AE1 and 0AE66 in the systems that increased either stocking rate, milk yield per cow or both respectively. Cows in the 'high milk yield per cow' systems had a significantly higher body condition score throughout the lactation, but reproductive performance was similar among all groups. Total pasture utilized (11 t DM ha )1 year )1 ) and pasture nutritive value were similar across all systems. This was associated with the grazing rules applied and the ability of accurately supplementing to meet deficits in available pasture. At the whole-system level, there was a higher marginal efficiency of supplement use when increasing stocking rate than when increasing milk yield per cow or increasing both (0AE18, 0AE07 and 0AE12 kg milk MJ )1 of metabolizable energy of supplements respectively).

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

“…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). Unlike Fariña et al (2011), who attributed much of the increase in milk production per hectare at higher SR to increased supplementation, the increased milk production per hectare achieved at higher SR in the present study is directly related to an increase in grazed herbage as supplementary feed imports were similar for each SR treatment (1,060 kg/ ha per year).…”

“…The biological effects of increased overall farm SR on milk production per hectare observed within our study are consistent with previous findings and further substantiate the potential for increased biological efficiency within higher-SR grazing systems. 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.…”

Differential response to stocking rates and feeding by two genotypes of Holstein-Friesian cows in a pasture-based automatic milking system

“…The criteria to define pasture allocations considered the following rules: (a) maintenance of pre-grazing herbage mass of 2000 kg DM/ha, (b) maintenance of post-grazing herbage mass or residual of 1200 kg DM/ha, (c) maintenance of an average herbage mass of 1600 kg/DM across the site and (d) an average consumption of 38 Mcal/day of metabolizable energy or the equivalent of 16 kg DM/cow in LSR or same 16 kg DM/cow from the combination of pasture and PMR in HSR. Therefore, PMR in HSR was used to minimize herbage deficits that resulted from the increase in stocking rate, but without sacrificing pasture growth rate (PGR), use of pasture/ha or modifying DMI (Fariña et al, 2011). The PMR was predominantly forage (Table 1) and formulated to a similar energy value as that of pasture.…”

“…As a general rule, greater milk response to supplementation is obtained in high stocking rate (HSR) systems because conditions that are necessary to minimize pasture substitution (i.e. low pasture allowance and/or herbage mass) can be achieved more easily (Fariña et al, 2011). On the other hand, the differential response to supplementation can vary widely between cows of different genetic merit, as shown by past comparisons of genotypes and their adaptability to pasture-based systems in conventional parlor milking systems (Kennedy et al, 2003;Horan et al, 2005;Fulkerson et al, 2008).…”

Effect of pre-grazing herbage mass on dairy cow performance, grass dry matter production and output from perennial ryegrass (Lolium perenne L.) pastures

“…The use of supplements during periods of pasture deficit avoided a reduction in milk yield per cow on the L treatment due to reduced pasture availability. A similar approach was used by Fariña et al (2011), which resulted in a similar milk yield per cow at a low (2.5 cows/ha) and high (3.8 cows/ha) SR.…”