Relationship between level of milk production and estrous behavior of lactating dairy cows.

摘要: The objective of this study was to determine if there is an association between level milk production and duration estrus as determined by standing activity recorded a radiotelemetry system. Holstein cows (n = 267; 50 DIM) were fitted with transmitter that allowed continuous recording activity. Cows housed in free-stall barn milked twice daily. Ovulation confirmed for all estruses 380). Average the 10 days before day used classify lower ( /= 39.5 kg/day) producers at time estrous expression. Follicle size serum estradiol (E(2)) concentrations subset 71) on estrus. Duration (6.2 +/- 0.5 h versus 10.9 0.7 h; P < 0.0001), events (6.3 0.4 8.8 0.6; 0.001), (21.7 1.3 s 28.2 1.9 s; 0.007) shorter from higher (46.4 kg/day; n 146) than (33.5 0.3 177). Milk correlated (r -0.51; 0.0001; 323). Higher had E(2) (6.8 0.5; 31 8.6 pg/ml; 40; 0.01) spite larger pre-ovulatory follicle diameter (18.6 0.3; 17.4 0.2 mm; 0.004). Interestingly, not -0.17; 0.15) but both -0.57; 0.0001) 0.45; 0.0001). Thus, high decreases probably due decreased circulating E(2).