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Use of Stochastic Simulation to Evaluate the Reduction in Methane Emissions and Improvement in Reproductive Efficiency from Routine Hormonal Interventions in Dairy Herds.

Archer SC, Hudson CD, Green MJ - PLoS ONE (2015)

Bottom Line: In some circumstances improvement in reproductive efficiency using the programmes investigated was associated with reduced cost and methane emissions compared to reliance on detection of oestrus.Efficiency of oestrus detection and the time to commencement of breeding after calving influenced variability in changes in cost and methane emissions.For an average UK herd this was a saving of at least £50 per cow and a 3.6% reduction in methane emissions per L of milk when timing of first insemination was pre-set.

View Article: PubMed Central - PubMed

Affiliation: School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire, United Kingdom.

ABSTRACT
This study predicts the magnitude and between herd variation in changes of methane emissions and production efficiency associated with interventions to improve reproductive efficiency in dairy cows. Data for 10,000 herds of 200 cows were simulated. Probability of conception was predicted daily from the start of the study (parturition) for each cow up to day 300 of lactation. Four scenarios of differing first insemination management were simulated for each herd using the same theoretical cows: A baseline scenario based on breeding from observed oestrus only, synchronisation of oestrus for pre-set first insemination using 2 methods, and a regime using prostaglandin treatments followed by first insemination to observed oestrus. Cows that did not conceive to first insemination were re-inseminated following detection of oestrus. For cows that conceived, gestation length was 280 days with cessation of milking 60 days before calving. Those cows not pregnant after 300 days of lactation were culled and replaced by a heifer. Daily milk yield was calculated for 730 days from the start of the study for each cow. Change in mean reproductive and economic outputs were summarised for each herd following the 3 interventions. For each scenario, methane emissions were determined by daily forage dry matter intake, forage quality, and cow replacement risk. Linear regression was used to summarise relationships. In some circumstances improvement in reproductive efficiency using the programmes investigated was associated with reduced cost and methane emissions compared to reliance on detection of oestrus. Efficiency of oestrus detection and the time to commencement of breeding after calving influenced variability in changes in cost and methane emissions. For an average UK herd this was a saving of at least £50 per cow and a 3.6% reduction in methane emissions per L of milk when timing of first insemination was pre-set.

No MeSH data available.


Related in: MedlinePlus

Model predictions of mean change in methane emissions (g per L of milk produced) through treatment of cows with up to 2 prostaglandin injections separated by an interval of 2 weeks prior to first insemination by 64 days in milk in herds with varying risk for cows being identified in oestrus and inseminated, and pregnancy risk compared to reliance on oestrus detection.Data for 10,000 herds of 200 cows were simulated (Table 2). Methane emissions per cow were estimated from daily forage dry matter intake, forage quality, and replacement risk. Cumulative milk yield per cow was estimated based on parity, stage of lactation, and stage of gestation. Methane emissions in the baseline scenario were subtracted to give the expected change in methane per L milk produced. Negative values indicate reductions. Associations with input parameters were evaluated in a linear model (Table 3); mean values were used to generate predictions.
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pone.0127846.g003: Model predictions of mean change in methane emissions (g per L of milk produced) through treatment of cows with up to 2 prostaglandin injections separated by an interval of 2 weeks prior to first insemination by 64 days in milk in herds with varying risk for cows being identified in oestrus and inseminated, and pregnancy risk compared to reliance on oestrus detection.Data for 10,000 herds of 200 cows were simulated (Table 2). Methane emissions per cow were estimated from daily forage dry matter intake, forage quality, and replacement risk. Cumulative milk yield per cow was estimated based on parity, stage of lactation, and stage of gestation. Methane emissions in the baseline scenario were subtracted to give the expected change in methane per L milk produced. Negative values indicate reductions. Associations with input parameters were evaluated in a linear model (Table 3); mean values were used to generate predictions.

Mentions: The major factors that determined changes in methane emissions are shown in the final models in Table 3. These models explained 36%, 41%, and 4% of the model variance for the Ovsynch, Ovsynch with progesterone, and double prostaglandin programmes respectively; residuals were distributed normally (Table 3). The impact of comparable changes in model input parameters (from the mean to the upper quartile) on change in methane emissions per L of milk with other inputs held at the mean is shown in Table 4; the Ovsynch based programmes (Groups 2 and 3) were most beneficial in herds with low submission risk, pregnancy risk, and voluntary waiting period. However the models included quadratic terms and interactions (Table 3) meaning the largest reductions in methane emissions per L of milk produced occurred in herds with the lowest submission risks, but otherwise good reproductive efficiency (voluntary waiting period < 50 days and high pregnancy risk; Fig 1). Further reductions in methane occurred through supplementing the Ovsynch programme (Group 2) with progesterone (Group 3) that increased with increasing pregnancy risk and decreasing submission risk (Fig 2). A similar trend was observed for the reduction in methane emissions associated with the double prostaglandin treatment (Fig 3), although the absolute reduction in methane was less than for the other programmes.


Use of Stochastic Simulation to Evaluate the Reduction in Methane Emissions and Improvement in Reproductive Efficiency from Routine Hormonal Interventions in Dairy Herds.

Archer SC, Hudson CD, Green MJ - PLoS ONE (2015)

Model predictions of mean change in methane emissions (g per L of milk produced) through treatment of cows with up to 2 prostaglandin injections separated by an interval of 2 weeks prior to first insemination by 64 days in milk in herds with varying risk for cows being identified in oestrus and inseminated, and pregnancy risk compared to reliance on oestrus detection.Data for 10,000 herds of 200 cows were simulated (Table 2). Methane emissions per cow were estimated from daily forage dry matter intake, forage quality, and replacement risk. Cumulative milk yield per cow was estimated based on parity, stage of lactation, and stage of gestation. Methane emissions in the baseline scenario were subtracted to give the expected change in methane per L milk produced. Negative values indicate reductions. Associations with input parameters were evaluated in a linear model (Table 3); mean values were used to generate predictions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4465033&req=5

pone.0127846.g003: Model predictions of mean change in methane emissions (g per L of milk produced) through treatment of cows with up to 2 prostaglandin injections separated by an interval of 2 weeks prior to first insemination by 64 days in milk in herds with varying risk for cows being identified in oestrus and inseminated, and pregnancy risk compared to reliance on oestrus detection.Data for 10,000 herds of 200 cows were simulated (Table 2). Methane emissions per cow were estimated from daily forage dry matter intake, forage quality, and replacement risk. Cumulative milk yield per cow was estimated based on parity, stage of lactation, and stage of gestation. Methane emissions in the baseline scenario were subtracted to give the expected change in methane per L milk produced. Negative values indicate reductions. Associations with input parameters were evaluated in a linear model (Table 3); mean values were used to generate predictions.
Mentions: The major factors that determined changes in methane emissions are shown in the final models in Table 3. These models explained 36%, 41%, and 4% of the model variance for the Ovsynch, Ovsynch with progesterone, and double prostaglandin programmes respectively; residuals were distributed normally (Table 3). The impact of comparable changes in model input parameters (from the mean to the upper quartile) on change in methane emissions per L of milk with other inputs held at the mean is shown in Table 4; the Ovsynch based programmes (Groups 2 and 3) were most beneficial in herds with low submission risk, pregnancy risk, and voluntary waiting period. However the models included quadratic terms and interactions (Table 3) meaning the largest reductions in methane emissions per L of milk produced occurred in herds with the lowest submission risks, but otherwise good reproductive efficiency (voluntary waiting period < 50 days and high pregnancy risk; Fig 1). Further reductions in methane occurred through supplementing the Ovsynch programme (Group 2) with progesterone (Group 3) that increased with increasing pregnancy risk and decreasing submission risk (Fig 2). A similar trend was observed for the reduction in methane emissions associated with the double prostaglandin treatment (Fig 3), although the absolute reduction in methane was less than for the other programmes.

Bottom Line: In some circumstances improvement in reproductive efficiency using the programmes investigated was associated with reduced cost and methane emissions compared to reliance on detection of oestrus.Efficiency of oestrus detection and the time to commencement of breeding after calving influenced variability in changes in cost and methane emissions.For an average UK herd this was a saving of at least £50 per cow and a 3.6% reduction in methane emissions per L of milk when timing of first insemination was pre-set.

View Article: PubMed Central - PubMed

Affiliation: School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire, United Kingdom.

ABSTRACT
This study predicts the magnitude and between herd variation in changes of methane emissions and production efficiency associated with interventions to improve reproductive efficiency in dairy cows. Data for 10,000 herds of 200 cows were simulated. Probability of conception was predicted daily from the start of the study (parturition) for each cow up to day 300 of lactation. Four scenarios of differing first insemination management were simulated for each herd using the same theoretical cows: A baseline scenario based on breeding from observed oestrus only, synchronisation of oestrus for pre-set first insemination using 2 methods, and a regime using prostaglandin treatments followed by first insemination to observed oestrus. Cows that did not conceive to first insemination were re-inseminated following detection of oestrus. For cows that conceived, gestation length was 280 days with cessation of milking 60 days before calving. Those cows not pregnant after 300 days of lactation were culled and replaced by a heifer. Daily milk yield was calculated for 730 days from the start of the study for each cow. Change in mean reproductive and economic outputs were summarised for each herd following the 3 interventions. For each scenario, methane emissions were determined by daily forage dry matter intake, forage quality, and cow replacement risk. Linear regression was used to summarise relationships. In some circumstances improvement in reproductive efficiency using the programmes investigated was associated with reduced cost and methane emissions compared to reliance on detection of oestrus. Efficiency of oestrus detection and the time to commencement of breeding after calving influenced variability in changes in cost and methane emissions. For an average UK herd this was a saving of at least £50 per cow and a 3.6% reduction in methane emissions per L of milk when timing of first insemination was pre-set.

No MeSH data available.


Related in: MedlinePlus