Invited Review: Treatment of Cows with an Extended Postpartum Anestrous Interval

Abstract

Cows with an extended interval from calving to first ovulation (PPI) have increased intervals from calving to conception and are more likely to be culled compared with cows with a short PPI. In year-round calving dairy herds, between 11 and 38% of cows are reported as anestrus by 50 or 60 d after calving. In seasonally calving dairy herds, between 13 and 48% of cows are diagnosed as anovulatory anestrus at the start of the breeding period. Ovulation and estrus after calving are delayed when the positive feedback effects of estradiol on release of LH from the pituitary, and circulating concentrations of metabolic hormones such as insulin and insulin-like growth factor-I, are reduced by a variety of environmental factors. The main factors are limited energy intake, lower body reserves, increased partitioning of energy to milk production, suckling, and peripartum disease. Treatment options for cows with an extended PPI include hormonal and management strategies. Hormonal treatments that include a period of progesterone supplementation result in the majority of treated animals displaying estrus with a subsequent luteal phase of normal duration and improved pregnancy rates compared with untreated controls. Hormonal interventions also tend to have more predictable outcomes compared with management changes, such as manipulating body condition or dietary intakes after calving, and usually have some estrous synchronization effect, thus facilitating the use of artificial insemination. However, responses to any treatment are variable and are related to those factors that influence duration of the PPI, such as body condition and parity.

Risk factors associated with detailed reproductive phenotypes in dairy and beef cows

“…The impact of negative energy balance on reproductive performance in dairy cows is well established (Beam and Butler, 1998). In agreement with the present study, stage of lactation has previously been shown to be associated with resumption of the ovarian cyclicity in both dairy (Rhodes et al, 2003;Gautam et al, 2010) and beef cows (Murphy et al, 1990) as well as the occurrence of cystic structures in dairy cows (Gröhn et al, 1994) and the uterine health of cows (Sheldon et al, 2008). As lactation progresses, energy balance improves (Berry et al, 2006), leading to more energy available for reproductive function and other bodily functions.…”

“…Previous studies have documented parity to be associated with the resumption of cycling in both dairy (Rhodes et al, 2003;Santos et al, 2009;Gautam et al, 2010) and beef (Stevenson et al, 1997) cows. The postpartum interval to return to normal ovarian cyclicity was longer in primiparous cows compared with multiparous cows (Santos et al, 2009).…”

“…The postpartum interval to return to normal ovarian cyclicity was longer in primiparous cows compared with multiparous cows (Santos et al, 2009). This longer interval to resumption of cyclicity in primiparous cows has been linked to greater nutritional stress in younger cows due to requirements for growth and lactation (Lucy, 2001;Rhodes et al, 2003). This is one reason why seasonal calving producers tend to calve heifers earlier than mature cows, thereby allowing primiparous cows a longer period from calving to the start of the herd's breeding season.…”

“…Scientific literature reviews, however, on both dairy and beef cows separately (Yavas and Walton, 2000;Rhodes et al, 2003;Crowe, 2008) suggest that beef cows have a greater incidence of prolonged postpartum anoestrous compared with dairy cows. The longer postpartum anoestrus period in beef cattle has been linked to the suckling effect (Rhodes et al, 2003). This is consistent with results in the present study where cows in beef herds in the present study were less likely to be cycling at the time of examination.…”

Detection of delayed cyclicity in dairy cows based on progesterone content in monthly milk samples

“…Darwash et al, 2001), but the response to different treatments varied considerably between and within herds (Rhodes et al, 2003). Even if hormonal interventions are successful, cows with extended anovulatory intervals postpartum may be presented for veterinary diagnosis and treatment very late after calving.…”