Short-term response in milk production, dry matter intake, and grazing behavior of dairy cows to changes in postgrazing sward height

摘要: Abstract Postgrazing sward height (PGSH) can be altered to adjust the allowance of grass in dairy cow's diet. This study aimed investigate short-term cow response a change postgrazing early lactation. Ninety Holstein Friesian spring-calving cows were randomly assigned across 3 treatments (n=30): 2.7cm (severe), 3.5cm (low), and 4.2cm (moderate) from February 14 April 24, 2011. From 25, animals rerandomized within each treatment graze 2 heights: (low) or 4.5cm (high). Animal production measurements taken 4 24 (measurement period 1; M1) 25 May 15 2; M2). The 6 (n=15) M2 severe-low, severe-high, low-low, low-high, moderate-low, moderate-high. During M1, increasing severe low moderate linearly increased daily milk yield (21.5, 24.6 25.8kg/cow per day) dry matter intake (GDMI; 13.2, 14.9, 15.8kg DM/cow day). Milk solids was reduced (−1,518g/cow when compared with (1,866g/cow day, on average). (MY) PGSH between M1 (V M1−M2 ) established using V MY=−1.27−1.89 × + 1.51 (R =0.64). MY associated (3 wk) −1.03kg/cow for 0.68kg/cow −2.56kg/cow −1.11kg/cow −4.17kg/cow −2.39kg/cow large increase energy severe-high achieved through higher GDMI minute bite, which supported positive MY. Treatments moderate-high recorded highest overall cumulative (74kg solids/cow) over 6-wk period, whereas severe-low had lowest (65kg MS/cow). animal responses observed present study, imposing spring provides opportunity thereafter; increases accordingly converts additional into output. equations this paper provide decision tool farmers anticipate is maintained around tenth week