@article{Mellado_Flores_Véliz_Santiago_García_Gutierrez_Mellado_2021, title={Impact of frequency of milking on milk yield and fertility of Holstein cows undergoing extended lactations due to failure to conceive}, volume={33}, url={https://ejfa.me/index.php/journal/article/view/2571}, DOI={10.9755/ejfa.2021.v33.i2.2571}, abstractNote={<p>The objective of this observational study was to determine the effect of two (2x) compared to three (3x) times a day milking in Holstein cows undergoing lactations ≥600 d on milk production and reproductive performance. Two large adjacent commercial dairy herds with similar size, facilities, and management in a hot area of northern Mexico (25° N) were used. Cows in one herd (n= 214) were milked two times a day (2x), the other herd was milked three times a day (3x; n=245) and both groups were milked for at least 600 days. For cows in first lactation, total milk yield did not differ between 3x and 2x cows (19796 ± 3354 <em>vs.</em> 19269 ± 3652 kg; <em>p </em>> 0.10) in lactations with an average of 696 and 650 days in milk (DIM), respectively. Multiparous 3x cows produced more total milk days than 2x cows (20942 ± 3920 vs. 18910 ± 2632 kg; <em>p < </em>0.01) with greater (<em>p < </em>0.01) DIM for 3x (685 ± 117 days) than 2x (631 ± 88 days) cows. Lactation persistence was greater (<em>p < </em>0.05) in 2x (62 ± 9%) than 3x (60 ± 10%) cows. Overall conception rate (CR) did not differ between 2x and 3x cows (53.3% <em>vs.</em> 49.8%) but 3x cows required one more service (<em>p < </em>0.01) to get pregnant than 2x animals.  Given that average milk yield throughout the complete lactation did not differ between 2x (29.8 ± 2.0 kg) and 3x (29.3 ± 2.9 kg) cows, it was concluded that <em>two</em>-<em>times-a-day milking</em> is equally effective as <em>three</em>-<em>times-a-day milking</em> to attain acceptable milk yield in lactations over 600 days. However, reproductive performance based on first-service CR and services per pregnancy was negatively affected by <em>three</em>-<em>times-a-day milking.</em></p>}, number={2}, journal={Emirates Journal of Food and Agriculture}, author={Mellado, Jesús and Flores, Jessica and Véliz, Francisco G. and Santiago, Ángeles de and García, José E. and Gutierrez, Hugo L. and Mellado, Miguel}, year={2021}, month={Mar.}, pages={113–119} }