Metabolic hormones, grazing behaviour, offspring physical distance and productive response of beef cow grazing at two herbage allowances

Abstract

Herbage allowance (HA) management during gestation–lactation cycle of cows grazing native grasslands improves pregnancy rates and calves’ weaning weight records. Those improvements were associated with greater herbage mass, and better body condition score (BCS) and metabolic status of the cows, which could affect grazing and maternal behaviour, particularly when temporary suckling restriction (TSR) and flushing (FL) is applied. The objective of this study was to evaluate the effect of HA during the gestation–lactation period on cows’ and calves’ liveweight (LW), BCS, milk yield, insulin, IGF-1 and leptin concentrations, as well as the proportion of diurnal grazing activities (grazing, ruminating, walking and idling), and maternal behaviour from −10 to 70 days relative to TSR (day 0 = initiation of TSR at 86 ± 10 days relative to calving). Thirty-three primiparous Hereford cows were allocated to HA treatments during gestation and lactation, which annually averaged 2.5 (low = LHA) and 4 kg DM/kg LW (high = HHA). The LW and BCS of cows did not differ during −10 to 50 days but were greater in HHA than LHA at the end of the study (P < 0.05). Concentrations of IGF-1 were greater in HHA compared to LHA, while insulin and leptin did not differ. Grazing was lower in HHA than LHA, and the opposite occurred with ruminating and idling (P < 0.05). Cow–calf physical distance was greater in LHA cows compared to HHA (P < 0.05) and increased greatly in the former group after FL, while this increase was lower and later in HHA cows. Milk yield was greater in HHA (P < 0.05), and calves’ weight did not differ between treatments from day −10 to 35, but was greater in HHA compared to LHA from 45 days until the end of the study. Thus, the HHA in a low herbage height and mass condition resulted in greater IGF-1 concentrations and milk yield, and induced changes in grazing and maternal behaviour that were associated with increased cows’ LW, BCS and calves’ weight at the end of the study.

Mobilizing Ecological Processes for Herbivore Production: Farmers and Researchers Learning Together

“…High HA led to moderate improvements in cow BCS (0.5 units) and energy intake (11%) during autumn. BCS and IGF-I concentrations were greater during winter, which led to more cows ovulating early in the next breeding season and successfully increased the herd reproductive response (Claramunt et al, 2020). This set of experiments has shown how the energy flow can be efficiently used in producing beef by maximizing energy consumption by cows and improving the energy partitioning in the animals (Do Carmo et al, 2016).…”

“…The main strategy elaborated with and implemented by farmers was to increase standing biomass and forage production of the grasslands by managing the grassland-herd interaction, increasing herbage allowance (HA) and adjusting allocation of animal categories to different paddocks according to standing biomass. Associated with suckling restriction and flushing, HA management modified energy partitioning between production and reproduction, which increased the efficiency of cow energy use (Soca et al, 2013a,b;Do Carmo et al, 2016;Claramunt et al, 2017Claramunt et al, , 2020. Management of HA required variation of stocking rate and/or sheep-tocattle ratio at the paddock or system scale and monitoring of standing biomass.…”

Native Grasslands at the Core: A New Paradigm of Intensification for the Campos of Southern South America to Increase Economic and Environmental Sustainability

“…In cow-calf experiments, Claramunt et al (2018) and Do Carmo et al 2018evidenced that monthly adjustments of the stocking rates to achieve target forage offer levels are key to increased animal productivity. Several case studies also demonstrated that stocking rate management at farm scale increased livestock production via higher calf weaning weights, pregnancy rates, and increased profitability (Albicette et al, 2017;Do Carmo et al, 2019;Claramunt and Meikle, 2020).…”

“…These management tools could help us to ensure adequate levels of body condition score at calving, and therefore higher annual pregnancy rates (Quintans et al, 2010, Soca et al, 2013Do Carmo et al, 2018), and to increase calf weight when suckling restriction is combined with a high forage offer (Claramunt and Meikle, 2020). Most of these tools were developed from the conceptual model proposed by Soca and Orcasberro (1992) that combine indicators of pasture structure and the energy balance of grazing cows to guide the management decisions in Campos ecosystems.…”