Effects of silage digestibility on intake and body reserves of dry cows and performance in the first part of the next lactation

Abstract

This experiment evaluated different strategies for allocating first-cut grass silages to dry dairy cows that had low body-condition score (BCS) at drying off. A total of 48 moderately yielding Holstein-Friesian cows were used, receiving one of three dietary treatments in the dry period and a single lactation diet based on a flat-rate of concentrates and grass silage ad libitum. Throughout the dry period, one group received a low-digestibility silage (harvested 15 June 1998; LL; metabolisable energy (ME) 5 10.3 MJ/kg dry matter (DM)) and a second group received a high-digestibility silage (harvested 9 May 1998, HH; ME 5 11.7 MJ/kg DM). A third strategy (LH) offered the low-digestibility silage in the early dry period and the high-digestibility silage in the final 3 weeks before calving. The silages had very different crude protein concentrations (144 and 201 g/kg DM) and intakes were widely divergent (10.1 v. 13.5 kg DM/day) across the dry period. No concentrates were fed during the dry period. Silage quality had a very large effect on liveweight change, with treatment means of 0.32 and 1.75 kg/day for LL and HH, respectively. BCS changes followed a similar pattern, though no cows became over-conditioned and blood metabolites were within normal ranges. Increased silage digestibility in the late dry period led to a substantial increase in milk fat concentration and a smaller increase in milk protein concentration, the latter confined to the first full week of lactation. Depression of milk fat appears related to low blood glucose when dry cows in low body condition are fed at a low level. The LH strategy avoided the tendency for lower milk yields and fat concentration that resulted from feeding the low-digestibility silage until calving. This strategy also avoided the higher calf weights that resulted from feeding the high-digestibility silage in the early dry period.

Effects of dietary energy allowance and decline in dry matter intake during the dry period on responses to glucose and insulin in transition dairy cows

“…The animal model approach applied in this study was chosen to ensure that the anticipated decline in DMI would actually happen in high EI cows during the close-up dry period. Experimental evidence of a dramatic decrease in DMI with grass silage-based diets is scarce, and the few studies conducted with these types of diets (Agenäs et al, 2003;Dewhurst et al, 2009) have not shown declines (up to 30% during the last 3 wk of pregnancy) as extreme as those reported by Grummer et al (2004) in mainly maize and alfalfa forage-based diets. Additionally, we assessed time and diet × time interactions of metabolic responses related to glucose and insulin dynamics in periparturient dairy cows.…”

“…The increase in DMI is fundamental for the adaptation to the abrupt change in energy requirements to support lactation. An excess allowance of energy in the dry period may result in a pronounced decline in DMI before parturition Douglas et al, 2006;Janovick and Drackley, 2010), although the decline in prepartal DMI is not universal (Agenäs et al, 2003;Dewhurst et al, 2009;Roche et al, 2013). However, overconditioning in the dry period has resulted in lower DMI in early lactation (Agenäs et al, 2003;Dann et al, 2006;Janovick and Drackley, 2010).…”

Effects of forage NDF content and body condition score on forage intake by Holstein–Friesian dairy cows in the dry period

“…Details of experimental procedures and results of individual experiments have been reported previously (Dewhurst et al, 2000a(Dewhurst et al, , 2000b(Dewhurst et al, , 2001(Dewhurst et al, and 2009Moorby et al, 2002). Animals and dry period diets All experiments involved Holstein-Friesian cows, approaching their second or subsequent calving.…”

“…Forage sampling and analysis procedures are described in the papers related to individual experiments (Dewhurst et al, 2000a(Dewhurst et al, , 2000b(Dewhurst et al, , 2001(Dewhurst et al, and 2009Moorby et al, 2002). Feed analysis is expressed on an oven DM basis (drying at 1008C until constant weight).…”

Effects of dietary energy allowance in grass silage-based diets during the dry period on production responses and utilization of body reserves in dairy cows

“…A common approach in supplying extra energy in the prepartum diet is to increase the level of concentrate in the ration (Remppis et al 2011). The research on the effect of GS allowance as sole feed in dairy cows during the FODP is limited to few studies (Dewhurst et al 2009, Little et al 2016. Accordingly, the effect of decreasing the oversupply of EI during the CUDP has not been studied experimentally on GS, although large changes in prepartal DMI have been linked to lower postpartal DMI (Grummer et al 2004).…”