Quantification by simulation of the effect of herd management practices and cow fertility on the reproductive and economic performance of Holstein dairy herds

Abstract

The performance of dairy herds is affected mainly by factors related to cows' characteristics and herd management practices. However, these factors are interrelated, and as such, the estimation of their individual effect on the performance of dairy herds remains difficult. The aim of this study was to estimate the weight of these factors as well the interactions between them on the reproductive and economic performance of dairy farms. A stochastic dynamic model was used to simulate most physiological and management processes occurring on a dairy farm. A herd of 60 Holstein cows, with a milk yield of 8,000 L/cow-year, representative of French Holstein dairy herds, was simulated. A total of 216 scenarios were run by combining 2 levels of postpartum cyclicity resumption (average: 45 d, high: 75 d), 3 levels of 21-d conception rate of the herd (i.e., proportion of cows pregnant 21 d after insemination; low: 25%, average: 45%, high: 70%), 3 levels of probability of pregnancy loss until 120 d (low: 3%, average: 15%, high: 43%), 3 levels of sensitivity of estrus detection by the farmer (low: 20%, average: 50%, high: 90%), 2 alternative managerial goals (constant number of cows or constant volume of milk sold), and 2 types of management for the sale and purchase of animals (closed or open herd). The effect of each factor was estimated by sensitivity analysis. The parameter that had the greatest effect on reproductive performance was the sensitivity of estrus detection: a 10-percentage-point increase between the low and average levels and between the average and high levels reduced the calving interval by 16 and 5.7 d, respectively. However, the factor that had the greatest effect on economic performance was the 21-d conception rate: a 10-percentage-point increase between the low and average levels and between the average and high levels increased the gross margin by €62.2 and €22.3/cow-year, respectively. The pregnancy loss until 120 d had an effect on economic performance: an increase of 1 percentage point of this parameter decreased the gross margin by €2/cow-year. The other factors studied, and their interactions, did not have a major effect (low value of sensitivity indices). Closed herds or farms with a constant number of cows had economic losses of €58/cow-year compared with open herds or to farms with constant volume of milk sold. Altogether, our data suggest that, in a typical French dairy farm, farmers' efforts on estrus detection will be more profitable when associated with improvement of the conception rate of the cows.

Evaluating the economic profit of reproductive performance through the integration of a dynamic programming model on a specific dairy farm

“…Higher reproductive performance determines faster 21-d PR establishment and, therefore, higher production of calves, which is translated into a higher net return. Previous research consistently agreed that greater calf sales or greater value of offspring are a consequence of improved reproductive efficiency (Cabrera 2012;Giordano et al 2012;Kalantari and Cabrera 2012;Galvao et al 2013;Bekara and Bareille 2019). Our study compared different 21-d PR for all evaluated farms and showed similar results.…”

“…Several authors have developed methodologies to estimate the financial cost of delayed pregnancy in dairy systems, based on computer simulation models (Groenendaal et al 2004;Meadows et al 2005;De Vries 2006;Kalantari and Cabrera 2015;Bekara and Bareille 2019). Although the use of those models made it possible to obtain quite realistic results, the real data from farms was not used in these studies, which could make it difficult to comprehend them by users.…”

“…The factor that had the greatest effect on economic performance was the 21-d conception rate: a 10-percentage-point increase between the low and average levels and between the average and high levels increased the gross margin by 62.2 and 22.3 EUR/per cow/year, respectively. The three levels of 21-d conception rate of the herd indicate the proportion of cows pregnant 21 d after insemination; low: 25%, average: 45%, high: 70% (Bekara and Bareille 2019). Conception rate influences days open because if a cow does not conceive, she will be open for an additional oestrous cycle (21 days) (Valergakis et al 2007).…”

“…The success of the reproductive management of all evaluated farms may be compared in more detail in Figure 1. Bekara and Bareille (2019) concluded that not every farm achieves a 365-day calving interval or a 5% culling rate for not-in-calf cows, but a significant amount of money can be gained by reducing the calving interval by as few as 10 days.…”

“…profitability) of changes in reproductive outcomes (Cabrera 2012). Many studies (Olynk and Wolf 2009;Giordano et al 2012;Galvao et al 2013;Kalantari and Cabrera 2015;Bekara and Bareille 2019) have attempted to quantify the economic impact of reproductive programs on specific dairy farms. However, reproductive performance might affect farm profitability differently.…”