Changes in herbage mass and time of herbage allocation modify nutritional and metabolic status of dairy cows

Abstract

In temperate milk production systems, it is important to study the effect of grazing strategies in both the quantity and quality of the diet, resulting in potential impacts on animal metabolism. The aim was to evaluate the effect of timing of herbage allocation and herbage mass on blood indicators. Forty Holstein-Friesian cows were grouped according to milk production (24.7 ± 2.8 kg cow-1), body weight (580.6 ± 51.7 kg) and days in milk (74 ± 17.1 d). The groups were randomly allocated to one of four treatments: 1) L-AM, access to new herbage allocation after morning milking with herbage mass of 2000 kg DM ha-1 ; 2) L-PM; access to new herbage allocation after afternoon milking with herbage mass of 2000 kg DM ha-1 ; 3) HAM ; access to new herbage allocation after morning milking with herbage mass of 3000 kg DM ha-1 ; 4) H-PM; access to new herbage allocation after afternoon milking with herbage mass of 3000 kg DM ha-1. Milk production was only different for H-PM in 1.1 kg higher than L-PM. Urea in milk was affected by treatments, being 22% higher for L-AM than other treatments. β-Hydroxybutyrate and blood urea concentrations were 47% and 30% higher, respectively, for AM compared to PM treatments. Plasma albumin concentration was lower for H-PM compared to other treatments at week 3 of blood sampling. PM treatments modify the herbage composition and animal metabolism, while combining it with a high herbage mass impacts positively in production and milk composition.

Black oat (Avena strigosa Schreb.) grazing or silage for small-scale dairy systems in the highlands of central Mexico. Part I. Crop and dairy cow performance

“…The nine cows were in three groups (squares) of three cows each according to similar parity, milk yield, and live weight following Morales et al (2018). Treatment sequences for the experiment were randomly assigned, and each cow within squares was also randomly assigned to sequence.…”

“…Chemical composition analyses for grazed herbage samples using the hand-plucking technique (simulating grazing) at the end of each experimental period (Morales et al, 2018), when samples of concentrate were also taken. Dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and in vitro DM digestibility (IVDMD) followed established procedures described by Celis-Alvarez et al (2016), and estimated metabolizable energy (eME) from AFRC (1993).…”

“…Recording of animal and pasture variables, and chemical analyses of feeds were as in Experiment 1. Sampling of BOS for chemical composition was at different points of the silage face, and pasture herbage samples were hand plucked simulating grazing (Morales et al, 2018). Determination of pH was in a dilution of silage with distilled water.…”

“…In dairy systems based on grazing, it is necessary to assess the effects of pasture quality and quantity in grazing strategies, so that research has been aimed at studying factors that affect herbage growth, quality and utilization, and the productive performance of dairy cows (Morales et al, 2018).…”

“…may be a better option, as a short cycle small-grain cereal tolerant to water deficit conditions and poor soils; prevalent in small scale systems in central Mexico, that affect feed production in terms of quantity and quality. A stable supply of forages during critical seasons or difficult conditions is required by dairy systems in other parts of the world as in Chile and in the Balkans (Morales et al, 2018;Radonjic et al, 2019).…”