Effect of stocking rate and calving date on dry matter intake, milk production, body weight, and body condition score in spring-calving, grass-fed dairy cows

Abstract

The primary objective of the study was to quantify the effect of stocking rate (SR) and calving date (CD) on milk production, dry matter intake (DMI), energy balance (EB), and milk production efficiency over 4 consecutive years (2009 to 2012). Two groups of Holstein-Friesian dairy cows with different mean CD were established from within the existing research herd at Moorepark (Teagasc, Ireland). Animals were assigned to either an early calving (mean CD February 14) treatment or a late calving (mean CD March 2) treatment. Animals within each CD treatment were randomly allocated to 1 of 3 whole-farm SR treatments: low (LSR; 2.51 cows/ha), medium (MSR; 2.92 cows/ha), and high (HSR; 3.28 cows/ha), and animals remained on the same farmlet for the duration of the study. Individual animal DMI was estimated 3 times per year at grass using the n-alkane technique in March (spring), May (summer), and September (autumn), corresponding to, on average, 45, 132, and 258 d in milk, respectively. A total of 138 spring-calving dairy cows were used during each year of the study. The effects of SR, CD, season, and their interaction were studied using mixed models. Individual animal milk production, body weight, body condition score, and the efficiency of milk production were significantly decreased as SR increased due to a reduction in herbage availability. The existence of CD × SR × season interactions for production, DMI, and EB indicate that delaying the herd mean CD can be an effective strategy to minimize the reduction in animal performance, particularly in spring at higher SR. This study further confirms the benefits of a new approach to the evaluation of herbage allowance known as the individual herbage allowance, which encompasses the 3 main factors restricting DMI in rotational grazing; namely, the average daily herbage allowance of the group, the intake capacity of the individual animal within the group, and the relative intake capacity of the animal within the competing herd.

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).…”

Mid-infrared spectrometry of milk as a predictor of energy intake and efficiency in lactating dairy cows

“…The basal diet of the majority of cows was grazed grass and the data originated from a range of grazing studies (Ganche et al, 2013a,b;McCarthy et al, 2014). Individual cow DMI was periodically recorded at grass using the n-alkane technique and fecal grab samples (Dillon and Stakelum, 1989) up to 8 times across lactation.…”

External validation of the GrazeIn model of pasture dry matter intake and milk yield prediction for cows managed at different calving dates and stocking rates

“…), defined as the number of animals per unit area of land used during a specified period of time (Allen et al, 2011), is acknowledged as the main driver of productivity (McCarthy et al, 2014). A recent review of several SR experiments, for which there was no additional supplement fed at the highest SR, reported a 0.20 increase in milk production per ha arising from a one cow per ha increase in SR (McCarthy et al, 2011).…”

“…In addition to SR, CD is an important determinant of feed utilization through its impact on the alignment between cow requirements and pasture supply (McCarthy et al, 2013), and altering the mean CD may have a relevant role in reducing the reliance of dairy farms on purchased feeds, particularly at high SR in early lactation (McCarthy et al, 2016). However, few studies (McCarthy et al, 2012a,b;2014) have attempted to quantify the effect of mean CD in spring on PDMI and MY or elucidate any potential interactions with SR.…”

“…Productivity within such grazing dairy systems depends on achieving a balance between the competing objectives of high pasture dry matter intake (PDMI) and milk yield (MY) per animal by maximizing pasture production per hectare, sward quality and pasture utilization (McCarthy et al, 2014;2016). This increase in milk production may be achieved by an increase in stocking rate (SR) in conjunction with the optimization of mean calving date (CD) at farm level (Dillon et al, 2008).…”