Pasture allowance, duration, and stage of lactation—Effects on early and total lactation animal performance

Abstract

Pasture availability in early spring can be limited due to climatic effects on grass production, increasing the likelihood of feed deficits in early lactation of springcalving pasture-based systems. We hypothesized that restricting pasture allowance (PA) when animals are at peak milk production will have more negative implications on milk production compared with restricting animals before this period. A total of 105 cows were assigned to 1 of 7 grazing treatments from March 14 to October 31, 2016 (33 wk). The control treatment was offered a PA to achieve a postgrazing sward height > 3.5 cm and mean pasture allowance of 15.5 kg of dry matter per cow. The remaining treatments were offered a PA representing 60% of that offered to the control for a duration of 2 or 6 wk from March 14 (mid-March; MMx2 and MMx6), March 28 (end of March; EMx2 and EMx6), or April 11 (mid-April; MAx2 and MAx6). Within grazing treatment, animals were also assigned to 1 of 2 calving dates (early and late) based on days in milk (DIM) on March 14. Early calved (EC) cows were ≥36 DIM, while late calved (LC) were ≤35 DIM. Restricting PA for 2 and 6 wk reduced daily milk yield (−1.6 and −2.2 kg/cow, respectively), cumulative milk protein yield (−4.0 and −6.3 kg/cow, respectively), and cumulative milk solids yield (−5.8 and −9.5 kg/ cow, respectively) in the first 10 wk of the experiment. Daily milk yield was similar across the treatments at the end of the 33-wk period (16.8 kg/cow, average of all treatments), as was daily milk solids yield (1.40 kg/ cow). Cows in the EC group produced less milk over the first 10 wk of the experiment (20.0 kg/cow per day) compared with the LC animals (22.1 kg/cow per day). However, body weight was greater (+15 kg/cow) in the EC animals compared with the LC, while body condi-tion score was similar (2.85). This outcome indicates that animals that are restricted later in early lactation (circa onset of peak milk production) partition a greater proportion of available energy to maintenance, resulting in greater losses in milk production. These data indicate that despite the immediate reduction in milk production, restricting intake of grazing cows to 80% of that required to achieve spring grazing targets for postgrazing sward height for up to 6 wk may be used as a method of managing short-term pasture deficits on farm with minimal effects on total lactation performance.

Sustainability of Lolium multiflorum L. “Ecotype Cajamarquino”, Associated with Trifolium repens L., at Three Harvest Times in the Northern Highlands of Peru

“…Our values exceed the annual yields of Mendoza et al ( 2018) [20], Rojas et al ( 2017) [27], [6] and Annicchiarico and Tomasoni (2010) [29], probably due to the establishment of these pastures associated for several decades -related to age, climatic conditions [18,19] that occur in the inter-Andean valley of the northern highlands of Peru, which is characterised by two well-defined climatic seasons during the year: rainfall and low water or drought; conditions that influence the productive behaviour of this forage association. From another perspective, when considering the time of year and the rainy season, the evaluated forage floor has a higher biomass accumulated per day, but there is no difference per cut.…”

“…From another perspective, when considering the time of year and the rainy season, the evaluated forage floor has a higher biomass accumulated per day, but there is no difference per cut. It should be considered that in rainy conditions, both the yield in kg DM ha −1 cut-1 and kg DM ha −1 year-1 was higher than the results referred by Claffey et al (2019) [18]; Tozer et al (2014) [19] and Mendoza et al (2018) [20], so in the rainy season the biomass productivity was higher than in the dry season by 18.74 %, a period that lasts about six months, adding that the areas under study, during the dry season, were irrigated fortnightly by flooding, but rainfall water affects productivity.…”

“…In addition to pasture management, the climatic characteristics of the time of year also affect the productive performance of the ryegrass-white clover association ( [18][19][20], with ryegrass showing more limitations in its growth during drought events [21] compared to white clover, which thanks to its variability responds with visible phenological changes to new environmental conditions, competing successfully against other plants [22,23]. White clover is characterised by its essential contribution of protein in the diet of animals [16] and by its capacity to fix nitrogen and improve the productivity of this association [23]; however, it has been found that values lower than 20 % of white clover in associated pastures seriously affect these indicators, in addition to restricting the total daily intake of nutrients.…”

The effect of nutritional management in early lactation and dairy cow genotype on milk production, metabolic status, and uterine recovery in a pasture-based system

“…Grazing cows fed very different planes of nutrition on a short-term basis may not show as substantial difference in performance (Burke et al, 2010;Claffey et al, 2019). However, where grazing cows have been fed different planes of nutrition in early lactation for longer periods (2 vs. 6 wk), performance differences are evident (Kennedy et al, 2015;Claffey et al, 2019). Furthermore, some of these performance differences extend beyond the time of nutritional treatment.…”

The effect of spring grass availability and silage supplementation on dairy cow performance and dry matter intake during early lactation

“…Dairy cows diets, particularly during early lactation, can have a significant impact on animal performance (Kennedy et al, 2007). Restricting DMI during early lactation has been shown to have a negative impact on subsequent milk production (Claffey et al, 2019b). Claffey et al (2020a) reported an increase in milk production of 0.38 kg milk/cow/day per kg DM increase in DHA.…”