Reproductive Indices in Determining Regular Calving of Holstein-Friesian Cows Maintained under Intensive and Semi-Intensive Managements in Central Java

Abstract

Reproductive efficiency of dairy cows can be determined by various reproductive indices (RIs) as essential components of regular calving period. The aims of this research were to assess some RIs, correlate among those RIs and describe possible causes of their variation for Holstein-Friesian (HF) cows maintained under two different conditions in Banyumas district, Central Java. Data of reproduction of HF cows were collected for 458 records from a dairy breeding station (BS), 1992 – 2002, and for 417 records from a number of small dairy holders (SDH), 1996 - 2002. A number of RIs studied were intervals from calving to first service (CFS), first service to conception (FSC), days open (DO) and calving interval (CI). Pearson correlation method was used to correlate (r) among RIs. Simple regression up to the third levels was used to investigate the effects of individual RIs (CFS and FSC) on DO and (CFS, FSC and DO) on CI. Means of each RI of HF cows between the BS and SDH were compared by the least square technique of GLM analysis by considering location, age-, seasonand year of calving as dependent variables. Location resulted in very significant effect (P<0.01) on CFS, DO and CI, at a range of 1.58 – 21.56 %. Adjusted means of CFS, FSC, DO and CI in the BS were 78, 22, 134 and 410 d respectively; and those in SDH were 91, 24, 156 and 427 d respectively. For both locations, FSC was a more major factor in affecting DO compared to CFS with the r value of FSC-DO almost twice the strength against CFS-DO (BS= 0.84 vs. 0.48; SDH= 0.82 vs. 0.44 %). Further, DO had the highest effect on CI compared to individual FSC or CFS, r value = 0.98 (the BS) and 0.97 (SDH. Lengthening each day of DO resulted in linearly increased CI of 0.99 d (the BS) and 0.98 (SDH). Major differences in RIs of HF cows in the current study compared to those in temperate and other tropical regions require definite researches in assessing various physiological and environmental factors affecting reproductive performance of HF cows under specific tropical region of Central Java.