Assessing the impact of lameness on fertility and oestrus behaviour of dairy cattle: A comparison of oestrus detection methods with the evaluation of a modern detection method

It is well documented that lameness is a painful and debilitating condition that can have adverse effects on welfare and reproductive performance, including oestrus expression and intensity. Despite extensive research, lameness continues to affect dairy cow populations. This study assessed the impact of lameness on fertility and oestrus behaviour of dairy cattle. The objectives of this research were: 1) to assess dairy producers’ perception of reproductive efficiency between lame and non-lame cattle, and to determine how they manage oestrus detection for lame cows; 2) to evaluate herd fertility parameters (number of days from calving to first service, number of days from calving to conception and the number of inseminations to conception) in lame and non-lame cows, to calculate lameness prevalence for the duration of the study, and to determine if access to pasture improves locomotion scores (LCS) and oestrus activity; 3) to compare common oestrus detection methods (Kamar®, EstrotectTM scratch cards, chalk, activity monitors (NeDap, IceQube®) in lame and non-lame cows, from pastured and housed conditions; and 4) to evaluate a new oestrus detection technology (Infrared Thermography (IRT)). Through an online questionnaire, it was determined that 85% of respondents noticed behavioural changes associated with lameness (reduced oestrus expression, less mounting activity, increased lying times), and that lame cows required more inseminations to conception (3.1 (±0.1) v 2.1 (±0.1); p<0.001). The majority of respondents use the same oestrus detection methods for all cows, despite behavioural differences between lame and non-lame cows stated by the respondents. Fertility assessment of dairy cows from Rodwell farm showed that lame cows had more days from calving to first AI (n=94 (n=25 lame; n=69 non-lame)) (63.8 v 53.5; p<0.01) and from calving to conception (n=69 (n=22 lame; n=47 non-lame)) (113.5 v 84.2; p<0.01). Evaluation of LCS showed that lameness prevalence decreased during the month’s cows had pasture access. Furthermore, there was significant improvement in LCS (by 0.21 units/week) after pasture access for all of study cows (both lame and non-lame) (p<0.001). Results showed that as the study cows LCS improved, subsequent oestrus activity (step counts, motion index) also increased thus indicating improved oestrus expression. Assessing multiple oestrus events from the study cows determined that there was a significant difference in the motion index (p<0.001), and the number of steps before, during and after oestrus from different LCS (p<0.001). Cows with a LCS of 1 at the time of oestrus had significantly more steps than a LCS of >2.5 during an oestrus event. Cows with a LCS of 1 at the time of oestrus had a significantly higher motion index than a LCS of >2 during an oestrus event. Housing affected activity, with housed cows having lower step counts (p<0.05), and reduced motion index (p<0.001). The mean LCS for oestrus events in housed conditions was higher than oestrus events occurring at pasture (2.5 v 1.9) (p<0.001). Comparison of oestrus detection methods between lame and non-lame cows revealed no significant difference (p>0.05). EstrotectTM scratch cards were more efficient at pasture than in housed conditions (p<0.05). Lame cows at pasture had fewer step counts (p<0.05), motion index (p<0.01), and fewer lying bouts when compared to non-lame cows (p<0.05) before, during or after oestrus. Housed lame cows had fewer step counts (p<0.05), motion index (p<0.05), fewer lying bouts (p<0.05), and increased lying bout lengths (p<0.05) when compared to non-lame cows before, during or after oestrus. Overall lame cows had lower progesterone values at 7 days (difference of 1.2 ±0.2 ng/ml; p<0.05) and 10-days (difference of 1.7±0.2ng/ml; p<0.001). Ongoing challenges in oestrus detection has led to advances in oestrus detection aids. Evaluation of a novel oestrus detection method (IRT) for lame and non-lame cows will determine its practicality for all cows. Based on the coefficient of variation the most reliable point to take IRT temperature measurements from is the pocket (under tail) (CV%; 0.6), and the eye (CV%; 1.3). However, the eye is more practical and its moderate positive correlation relationship (R2=0.45) to the core body temperature makes it appealing. Comparison of baseline temperatures with temperatures recorded when the cow is in oestrus revealed a significant increase in the core (+0.59°C; p<0.001), eye (+0.58°C; p<0.001), ear (+0.48°C; p<0.05), and pocket (+0.66°C; p<0.001) temperatures. Lame cows had significantly reduced temperatures (baseline & oestrus) from the core (p<0.01), eye (p<0.001), pocket (p<0.001), and pin (p<0.05) locations compared to non-lame cows. IRT can be implemented to identify oestrus in lame and non-lame cows, in addition to potentially detecting lameness based on temperature readings. These studies demonstrate that lameness affects fertility and physiological parameters. Activity during oestrus can be increased if locomotion scores can be improved. Reducing lameness will enhance animal welfare and productivity. IRT can accurately identify cows in oestrus, and has the potential to identify lame cows, as they had reduced temperatures when compared to non-lame cows. This study provides an insight for the potential of IRT for increasing oestrus detection, and for automated lameness detection.