A longitudinal study of oestrous characteristics and conception in tie-stalled and loose-housed Swedish dairy cows

Abstract

The presence and importance of visual oestrous symptoms and the relation to conception, breed, housing system and milk yield were studied. Data were collected from a Swedish research herd during a 16-year period. Local, secondary and primary oestrous symptoms and an overall oestrus intensity score (OI) were studied. Decreasing trends in oestrous expression and conception rates (CR), and an increase in CR with more intensive oestrus, from 24% at OI score one (very week) to 54% at OI score five (very strong) were observed. The mean interval from first to last observed oestrus symptom was long with a large variation (54 ± SD = 32 h). Generally, irrespectively of housing system, Swedish Red cows had higher CR, more intensive oestruses and longer oestrus durations compared to Swedish Holstein cows. Local oestrous symptoms, with CR of 24-28%, were most frequently detected, which is why more attention should be paid to local oestrous symptoms.ARTICLE HISTORY

Extent and pattern of pregnancy losses and progesterone levels during gestation in Swedish Red and Swedish Holstein dairy cows

“…The lower total pregnancy loss for SR cows is in agreement with our earlier study where we found higher conception rates in SR cows than in SH cows based on transrectal pregnancy checks at approximately day 60 after AI [ 19 ]. Data on the effect of breed are very sparse in the literature.…”

“…Early embryonic loss decreased with stronger oestrous expression, which was not surprising because our earlier study showed a positive association between oestrus intensity and conception rates [ 19 ]. These results are also in agreement with Pereira et al [ 28 ], who reported that a decrease in pregnancy losses (between 32 and 60 days of pregnancy) associates with cows expressing oestrus compared to no oestrus using protocols for timed insemination or timed embryo transfer.…”

“…An oestrous cycle, which averages 21 days, is defined as the period initiated by an increase in P4 and subsequently terminated with the next decrease below the threshold value, if the cow is not pregnant. Atypical P4 profiles show deviating P4 concentration pattern, and have been associated with longer calving to first service and calving intervals, as well as reduced conception rates [ 17 – 19 ].…”

“…Nyman et al [ 19 ] reported that, cows with a more intensive oestrus have a greater chance to be pregnant at day 60 post AI, and they also reported that Swedish Red cows have stronger oestrous expression and better conception rates compared to SH cows. It remains to be investigated if these findings also result in higher calving rates.…”

Estrous activity in lactating cows with divergent genetic merit for fertility traits

“…We did not find an association between any estrous characteristics and conception to AI. This is inconsistent with previous studies that report a positive association between estrous intensity or peak activity and conception rate (Madureira et al, 2015;Nyman et al, 2016). The lack of association in our study suggests estrous traits and conception traits could be selected separately.…”