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Reproductive Performance and Breeding

Improve reproductive performances for profitability and serenity

Getting dairy cows pregnant after calving is a major challenge for most dairy operations. Typically, dairy cows recover ovarian activity around 35 days after calving, and uterine involution is complete 50 days after calving, allowing for a new pregnancy.  

All over the world, high-yielding cows show increasing reproductive difficulties to get pregnant in a reasonable time after calving, leading then to extended average days in milk and lower average daily milk yield. Moreover, cows with extended days in milk have lower feed efficiency and decreased milk income over feed cost.  

In a recent study, reproduction of lactating cows was ranked in the top 3 difficulties or challenges by 66% of dairy farmers, and heat detection and conception risk were the most cited issues (Denis-Robichaud et al., 2018). 

Poor reproductive performances are also associated with a higher probability of culling (more than x4 compared to other cows, De Vries et al., 2010) and lesser possibilities of culling for other reasons. As it has direct consequences on milk production and culling probability, the economic impact of low fertility rates is of importance.  

A recent study showed a positive and quadratic relationship between 21-day pregnancy rate and economic net return (USD/cow per year)  (Cabrera, 2014). Moreover, combined with low conception rate, insufficient heat detection was estimated to decrease gross margin up to 20% (Seegers, 2006).

Age at first calving

Replacement heifers, as unproductive animals, should be considered as a cost. Thus the quicker the age at first calving, the quicker the return on investment. Age at first calving between 23 to 24.5 months have been associated with better performances, health and income in first lactation of Holstein cows (Ettema and Santos, 2004). 

Breeding difficulties in modern dairy operations

Many studies worldwide report a reduction of reproductive performances with increased milk productivity. But exploring biological mechanisms reveals that, more than productivity itself, energy balance is the main driver of reproductive performances. Energy balance in early lactation is positively correlated with conception rate and earlier resumption of cyclicity, whereas no relationship was found with milk yield (Patton et al., 2007).  

The prevalence of subclinical ketosis in early lactation is estimated around 20% in commercial farms, with high variability among herds (Suthar et al., 2013), and has been associated with delayed onset of ovarian activity, anovulation (Dubuc et al., 2012) and shorter estrus duration (Rutherford et al., 2016). Lower energy status in early lactation is also associated with subsequent development of endometritis (Yasui et al., 2014). 

As most of dairy operations use artificial insemination as breeding practice, heat detection is a key factor for successful reproductive performances, but can be impaired by both animal and management-related factors. Although standing to be mounted is the most reliable sign of estrus in cows, its expression is highly variable on commercial farms, and is markedly reduced in high yielding cows (Cutullic et al., 2010). Thus proper heat detection is more challenging in herds with high productivity. Dark barns and slippery walking areas also have a negative influence on heat expression. 

Environmental factors may also impair reproductive performances. Several diseases have been reported to impact fertility. Poor hygiene is also detrimental through increased risk of metritis. As climatic factor, heat stress is particularly detrimental to conception rates (Biffani et al., 2016). 

Concerning replacement heifers, their aptitude to calve within the targeted age is good, and challenges are rather related to management issues starting from early life to breeding. 

Strategies to get more cows pregnant 

Genetics cannot solve existing short-term issues, but surely is a relevant strategy to improve long-term reproductive performances. Selection on genetic merit for fertility traits is efficient to shorten calving to conception interval, reduce services per conception while increasing milk yield (Cummins et al., 2012).  

A healthy reproductive tract and uterus able to support a young fetus is crucial. Health conditions and production are interrelated.  Reproduction efficiency can be affected by ketosis, dystocia and retained placenta, but it is not directly associated with milk fever, displaced abomasum, and mastitis. The primary ways to influence reproduction are from an energy basis and specific uterine health. 

5 tips to overcome reproductive issues:  

  1. Minimize negative energy balance in early lactation 
  2. Monitor body condition scoring (BCS) 
  3. Feed bunk management 
  4. Ensure environmental comfort (light, flooring, facility design) 
  5. Record heat detection procedures and document data  

Among short-term strategies, strong focus should be given on minimizing negative energy balance in early lactation, during which cows cannot consume enough feed to meet their energy needs. Severe negative energy balance brings increased uterine inflammation, providing a poor chance for fertilization and implantation.   

Several studies recently highlighted the importance of the whole transition period to improve dry matter intake, energy balance and milk production in early lactation, and prevent from associated disorders.  

On farm, estimation and monitoring of energy balance can be achieved through body condition scoring (BCS) from calving to early lactation. BCS loss in early lactation have been shown to be strongly associated with decreased conception rate, higher days open and higher frequency of health disorders (Middleton et al., 2019). In order to improve energy balance during the first 100 days in milk, energy intake should be encouraged through high energy density diets, with an emphasis on carbohydrates as they are best glucose precursors.  

Diet intake should also be stimulated through feed bunk management. This point is critical, as high carbohydrates diets are more susceptible to trigger ruminal acidosis, leaky gut and inflammation. Prolonged time with empty bunk increases the risk of leaky gut, and competition at the feed bunk increases eating rate and sorting against long particles (Crossley et al., 2017). Ruminal acidosis and subsequent leaky gut cause liver damage and may be responsible for inflammation with negative consequence on corpus luteum lifespan (Lüttgenau et al., 2016). 

Barn conception and facilities should provide maximum comfort to help cows expressing heat behavior and interaction with other cows: sufficient light, non-slip walking surfaces, appropriate free stalls dimensions to avoid lameness. Barn facilities must also include specific calving pens to ensure comfort and maximum hygiene for calving operations.  

As high producing cows tend to express fewer standing heat behavior, increased initiated secondary estrus signs (anogenital sniff, chin rest, attempt to mount) must be taken in consideration for heat detection, even though they are less reliable. Heat detection procedures should be determined and shared by all individuals involved, and all events linked with reproduction should be reported in a common system to ensure a monitoring of breeding operations, and offer the possibility to investigate causes of past poor performances.

Troubleshooting reproductive issues 

Linked to, but beyond energy intake, is the need for cows to perform as efficiently as possible, including absorption of nutrients from the gut, and an effective liver that can package and distribute nutrients needed by tissues. 

The liver is critical for glucose production and redistribution of fat for use by other tissues, particularly in early lactation when both are in high demand.  The liver is the first organ (after the gut itself) exposed to nutrients and other compounds absorbed and transported to the blood. Toxins that decrease liver function negatively affect a cow’s energy balance. Key phytogenic products have been demonstrated to improve liver health, support proper immune function and increase dry matter intake. 

Mycotoxins in cattle feed and forage can reduce feed intake, impair immune function and disrupt reproductive efficiency. Products that reduce the effects of mycotoxins are likely to assist in improving reproductive efficiency. In addition to proper management and supplying balanced rations, producers can use selected additives to prevent or reduce problems associated with breeding difficulties.  


Potential causes

Uterine Infections
Poor immune function

Toxin issues including:  

  • Potential nitrate poisoning, alkaloids (plant origins) 
  • Mycotoxins including aflatoxin, deoxynivalenol, T-2, ochratoxin A 
  • Other immune demands, general infections 
Poor uterine involution 

Decreased liver function:  

  • Fatty liver syndrome, decreased nutrients provided 
  • Mycotoxins affecting the liver (aflatoxin, deoxynivalenol, T-2) 

Mycotoxins’ direct effect on the uterus: zearalenone causes estrogenic effects and may results in uterine infections and vaginitis     

Energy Balance
Liver functionDecreased liver efficiency due to mycotoxicosis including aflatoxins, deoxynivalenol, T-2, ochratoxin A 
Decreased feed intake 

Poor feed consumption just prior to and just after calving (pre-fresh feeding 


Toxins from plants, molds and fungi (mycotoxins) 

Formulation including palatability, digestibility and nutrient density 

Reproduction performance
Impaired reproduction system

Toxin issues including:  

  • Mycotoxins: mainly zearalenone, but also including ergot alkaloids and type A and B trichothecenes
Zearalenone: besides uterine infections and vaginitis, conception rates can be decreased. Infertility, abortions, teat enlargement, udder secretions, low testicular development, low sperm production, and more can occur.


  • Improving reproductive performances increases profitability, but requires strict management and well balanced diets. Because of its very strong impact on ovarian activity and conception rate, special care should be set on improving energy balance in early lactation. High carbohydrates diets efficiently improve energy balance but increase the risk of acidosis, leaky gut and inflammation. Feed additives that improve rumen health and liver function will help preventing those risks.


Biffani, Bernabucci, Vitali, Lacetera, and Nardone. 2016. Short communication: Effect of heat stress on nonreturn rate of Italian Holstein cows. J. Dairy Sci. 99:5837–5843 

Cabrera. 2014. Economics of fertility in high-yielding dairy cows on confined TMR systems. Animal 8:s1, pp 211–221 

Cutullic, Delaby, Gallard and Disenhaus. 2010. Dairy cows’ reproductive response to feeding level differs according to the reproductive stage and the breed. Animal, 5:5, pp 731–740 

Cummins, Lonergan, Evans, Berry, Evans, and Butler. 2012. Genetic merit for fertility traits in Holstein cows: I. Production characteristics and reproductive efficiency in a pasture-based system. J. Dairy Sci. 95 :1310–1322 

Crossley, Harlander-Matauschek, and DeVries. 2017. Variability in behavior and production among dairy cows fed under differing levels of competition. J. Dairy Sci. 100:3825–3838 

Denis-Robichaud, Cerri, Jones-Bitton, LeBlanc. 2018. Dairy producers’ attitudes toward reproductive management and performance on Canadian dairy farms. J. Dairy Sci. 101:850–860 

Dubuc, Duffield, Leslie, Walton, and LeBlanc. 2012. Risk factors and effects of postpartum anovulation in dairy cows. J. Dairy Sci. 95 :1845–1854 

De Vries, Olson, Pinedo. 2010. Reproductive risk factors for culling and productive life in large dairy herds in the eastern United States between 2001 and 2006. J. Dairy Sci. 93 :613–623 

Ettema and Santos. 2004. Impact of Age at Calving on Lactation, Reproduction, Health, and Income in First-Parity Holsteins on Commercial Farms. J. Dairy Sci. 87:2730–2742 

Lüttgenau, Lingemann, Wellnitz, Hankele, Schmicke, Ulbrich, Bruckmaier, and Bollwein. 2016. Repeated intrauterine infusions of lipopolysaccharide alter gene expression and lifespan of the bovine corpus luteum. J. Dairy Sci. 99:6639–6653 

Middleton, Minela, and Pursley. 2019. The high-fertility cycle: How timely pregnancies in one lactation may lead to less body condition loss, fewer health issues, greater fertility, and reduced early pregnancy losses in the next lactation. J. Dairy Sci. 102:5577–5587 

Seegers. 2006. Economics of the reproductive performance of dairy herds. World Buiatrics Congress 

Patton, Kenny, McNamara, Mee, O’Mara, Diskin, and Murphy. 2007. Relationships Among Milk Production, Energy Balance, Plasma Analytes, and Reproduction in Holstein-Friesian Cows. J. Dairy Sci. 90:649–658 

Rutherford, Oikonomou and Smith. 2016. The effect of subclinical ketosis on activity at estrus and reproductive performance in dairy cattle. J. Dairy Sci. 99:4808–4815 

Suthar, Canelas-Raposo, Deniz, and Heuwieser. 2013. Prevalence of subclinical ketosis and relationships with postpartum diseases in European dairy cows. J. Dairy Sci. 96 :2925–2938 

Yasui, McCann, Gilbert, Nydam, and Overton. 2014. Associations of cytological endometritis with energy metabolism and inflammation during the periparturient period and early lactation in dairy cows. J. Dairy Sci. 97 :2763–2770 



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