Does body size of dairy cows, at constant ratio of maintenance to production requirements, affect productivity in a pasture‐based production system?

Abstract

This study compared productivity of dairy cows with different body weight (BW), but a constant ratio of maintenance to production requirements in their first lactation, in a pasture-based production system with spring calving. Two herds, Herd L (13 and 14 large cows in 2003 and 2004 respectively; average BW after calving, 721 kg) and Herd S (16 small cows in both years; 606 kg) [Correction added after online publication 14 January 2011: 16 small cows in both years; 621 kg was changed to 16 small cows in both years; 606 kg], all in their second or following lactations, were each allocated 6 ha of pasture and rotationally grazed on 10 parallel paddocks with equal herbage offer and nutritional values. Winter hay, harvested from the same pastures, was offered ad libitum in the indoor periods in a tied stall barn. Each herd received, per lactation and year, approximately 2000 kg dry matter (DM) of concentrates and of fodder beets, equally distributed to every individual. Indoors, the L-cows ingested more DM than the S-cows (18.7 vs. 16.3 kg DM/cow per day; p < 0.01), but DM intake per 100 kg of metabolic BW was similar (13.0 vs. 13.1 kg DM/cow per day). Estimates based on the n-alkane technique gave similar results on pasture (17.9 vs. 15.5 kg DM/cow per day; p < 0.001). Roughage intakes per 100 kg of metabolic BW, at 13.5 kg DM/cow per day, were similar. Mean annual yield of energy-corrected milk (ECM)/ha was slightly higher for the S-herd than the L-herd (13,026 vs. 12,284 kg) but was associated with a higher stocking rate (on average +20%) for the S-herd. Feed conversion efficiency (1.2 vs. 1.3 kg ECM/kg DM intake) and overall milk production efficiency (45.3 vs. 47.3 kg ECM/kg metabolic BW) were similar in L- and S-cows. Thus, both dairy cow types were equally efficient in utilising pasture-based forage.

Dairy farming: indoorv.pasture-based feeding

“…Productivity (kg ECM/ha AL) was high in the IF herd compared with the PF due to the higher energy and protein content of the feed ration, the higher feed intake and the higher milk production. The productivity of the PF herd was lower than the results reported by Hofstetter et al (2011), who used a rotational grazing system, and also lower than the findings of both McEvoy et al (2009) and Curran et al (2010). Their swards, however, were already adapted to the PF system, whereas the swards in the present study were used as semi-continuous pastureland for the first time.…”

“…For PF, a seasonal, spring-calving, low-input, semicontinuous, pasture-based production system (Durgiai 1996;Münger & Jans 2001) with 28 dairy cows was established. In the PF herd, the target level was 6000 kg milk per lactation and cow, determined in Dairy farming: indoor v. pasture-based feeding accordance with previous pasture-based production system studies (Thomet et al 2010;Hofstetter et al 2011). At the beginning of each lactation, the PF cows were fed hay ad libitum, supplemented by limited amounts of concentrate.…”

“…On the basis of previous studies (Bargo et al 2002;Fontaneli et al 2005;Vibart et al 2008), the following hypotheses were tested: (i) IF dairy cows are more efficient than PF dairy cows; (ii) based on a previous study (Münger & Jans 2001;Hofstetter et al 2011), the land productivity of the herds would be similar; and (iii) the labour income of the PF herd would be higher (Durgiai 1996;Gazzarin & Schick 2004;Gazzarin et al 2005).…”

Performance, body fat reserves and plasma metabolites in Brown Swiss dairy cows: Indoor feeding versus pasture‐based feeding

“…For PF, a pasture‐based production system with seasonal calving in spring was established in a herd of 13.8 ± 0.3 BS cows. In the PF herd, the target lactational performance level of 6,000 kg of milk in accordance with observations from a previous pasture‐based study (Hofstetter et al., ). After calving, the PF cows had free access to hay, but were supplemented with only limited amounts of concentrate.…”

Towards an agroecological assessment of dairy systems: proposal for a set of criteria suited to mountain farming

“…Criterion 3: The farmers may also favour the choice of genotypes (breed, strain and format) best fitted to grasslandbased diets with a low amount of concentrates (Horan et al, 2005;Hofstetter et al, 2011), that is, genotypes able to meet their requirements by developing specific adaptations, both behavioural (land exploration, selective intake) and physiological, to maintain milk production and reproductive efficiency under harsh feeding conditions (Blanc et al, 2006). In the future, progress in genomic selection should help in choosing cows adapted to mountain grass-based diets, by a direct selection on traits related to digestive efficiency (Veerkamp et al, 2012).…”