Understanding Postpartum Anestrus and Puberty Dr. Jack C. Whittier, Colorado State University Dr. Jim Berardinelli, Montana State University Dr. Les Anderson, University of Kentucky 2008 Robert E. Taylor Memorial Symposium
Anestrus? Anestrus is the primary factor reducing reproductive efficiency in beef cow-calf operations. Anestrus can be defined as the lack or absence of the expression of estrus. Anestrus occurs annually; heifers are anestrus prior to puberty and anestrus occurs in cows after each calving.
Causes of Anestrus Before puberty (prepuberal anestrus) After calving (postpartum anestrus) Biological protection for dam and offspring Lactational Nutritional If the environment is not suitable for the dam, why bring a competing calf into this environment Every other year calving in harsh environments Seasonal (ewe, mare) Pregnancy
Factors Contributing to Infertility General Infertility Biological Ceiling 25% to 30% effect Uterine Involution Short Estrous Cycles Anestrus Potential for manipulation through management
Relationship of Fertility to Time After Calving Short et al., 1990
% Anestrus Females Incidence of Anestrus* in US Beef Cattle at Start of Breeding Season 60 50 40 30 20 Range 17-67% 851 cows at 6 locations Nursing Calves Range 6-81% 724 heifers 5 locations 10 0 56 days postpartum Postpartum Cows *Based on blood samples for progesterone 14.7 months of age Yearling Heifers Lucy et al., 2001
Percent of Cows Cyclic by Year (~ 60 d postpartum) % of all cow s 75 60 45 30 15 % Cyclic 35 47 45 68 61 0 1994 1995 1996 1997 1999 Year (Jackson Branch of the OSU Ag Experiment Station, Jackson, OH)
What Is Anestrus Physiologically?
Postpartum Anestrus in Beef Cows Structure Diameter 1 st DF Anestrus 45 to 90+ days in US Beef Cows Estrogen inhibitory! * * Progesterone 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Days Relative to Calving Calving First Estrus
Depth of Postpartum Anestrus in Beef Cows Hormone Concentration Estrogen inhibitory! Anestrus GnRH/CIDR Protocols Effective Increasing Depth of Anestrus Estrogen stimulatory! Peri- Estrus Progesterone -55-50 -45-40 -35-30 -25-20 -15-10 -5 0 60 65 70 75 Days Relative to First Estrus First Estrus
Factors Regulating the Length of Anestrus Presence of the calf Initiates anestrus Body Condition Score (BCS) Parity Days Since Calving Other factors include dystocia, health, and calving season (fall vs. spring)
Presence of the Calf
Presence of the Calf Presence of the calf initiates anestrus Establishes the negative feedback of estrogen on the hypothalamus Results in low LH pulse frequency Exact mechanisms unknown but both the physical contact of the calf (nursing) and the mere presence of the calf at side are involved Short-term calf removal (48 h) has been shown to be an effective method to induce estrus GnRH/CIDR synch protocols appear to mimic this response
Stevenson et al., 1994 Is it presence of calf, nursing, or other? Four treatments: Mastectomized, calf weaned at birth Mastecomtized, calf restricted to non-inguinal contact (head and neck of cows restricted by pen and panel barriers) Mastectomized, unrestricted calf presence Udder intact, unrestricted calf presence
Results Stevenson et al., 1994 Unrestricted presence of calf prolonged anestrus in both intact and mastectomized cows A cow must receive stimuli resembling normal suckling to prolong anestrus whether intact or mastectomized
Bull effect Presence or Absence of the Bull Presence of male (boar, ram) Several studies indicate a positive response to bull exposure Intact Sterilized Androgenized cows or steers Does putting the bull with the cows at the beginning of the breeding season have the same effect?
Jim Berardinelli, Ph.D. Department of Animal and Range Sciences Montana Agricultural Experiment Station Montana State University Bozeman 17
Biostimulatory effect of bulls (MSU & Others) Presence of bulls accelerates resumption of estrous cycles; decreasing length of anestrus. In bos taurus & indicus cows 18
Table 1. The biostimulatory effect of bulls in primiparous and multiparous cows (adapted from Custer et al., 1990; and Stumpf et al. 1992, respectively). Primiparous cows Multiparous cows Variable NE BE diff NE BE diff Postpartum interval to anestrus, d 82 ± 9 a 64 ± 6 b 18 58 ± 2 a 44 ± 2 b 14 a,b Means that lack a common superscript differ (P < 0.05). 19
What we know about the biostimulatory effect of bulls (MSU) 1.Caused by pheromone(s) produced by bulls (Berardinelli and Joshi, 2005b). 2.Does not appear to work before 35 d after calving in suckled cows (Fernandez et al., 1993. 20
What we know about the biostimulatory effect of bulls (MSU & Others) 3.Works better as time after calving increases after 35 d (Berardinelli and Joshi, 2005a). 4.Bulls > 18 mo old and androgenized cows have same affect as mature bulls (Cupp et al., 1990; Burns and Spitzer, 1992). 21
What we know about the biostimulatory effect of bulls (MSU) 5.Intermittent exposure does not work (Fernandez et al., 1996). 6.Twelve hour exposure does work (Berardinelli and Joshi, 2005b). 22
What we know about the biostimulatory effect of bulls (MSU & Others) 7.Fence line contact under certain conditions will work (Fike et al., 1996; Berardinelli and Tauck, 2007). 8.Continuous exposure to bulls urine does not work (Tauck et al., 2006) 23
it appears to enhance pregnancy when used in conjunction with GnRH and progesterone based estrous synchronization protocols that incorporate fixed time AI (Berardinelli and Tauck, 2007; Tauck and Berardinelli, 2007). effect of bulls not only increases the number of suckled cows that begin cycling before the breeding season, but that AI pregnancy rates are significantly improved by the biostimulatory effect of bulls. 24
Body Condition
Body Condition Score (BCS) Body Condition Score is an estimate of the degree of fatness of an animal 1 = emaciated 9 = extremely obese Estimate of available energy stores
Uses of Nutrients and Energy Unnecessary energy reserves (BCS > 6) Estrous cycles Additional energy reserves (BCS = 4-5) Lactation Pregnancy Basic energy reserves (fat) Nutrients Growth Activity Basal Metabolism
Influence of BCS at Calving on Anestrus % Cycling 100% 80% 60% 40% 20% 0% 71 80 59 49 42 25 157 481 726 1,002 337 188 <3.5 4 4.5 5 5.5 >6 Body Condition Score Source: Stevenson et al., 2003
Interaction of BCS at Calving and Postcalving Nutrition Days to first postpartum estrus 100 80 60 40 20 0 Postcalving Nutrition High Adequate (100% NRC) Low 1 2 3 4 5 6 7 8 9 10 Body condition score at calving Source: Short, 1990
Parity Young cows (2 year old suckled cows) simply require 20-30 more days to resume estrous cycles Recommendation has always been to calve first parity cows 20-30 days before the mature cow herd Stevenson et al., 2003 Parity Days PP Percent Cyclic 1 86 55 2 68 64
Uses of Nutrients and Energy Unnecessary energy reserves (BCS > 6) Estrous cycles Additional energy reserves (BCS = 4-5) Lactation Pregnancy Basic energy reserves (fat) Nutrients Growth Activity Basal Metabolism
Influence of Days Since Calving
Influence of Days Since Calving on Anestrus % Cycling 80 70 60 50 40 30 20 10 0 70 62 55 62 44 45 25 9 <30 31-40 41-50 51-60 61-70 71-80 81-90 >90 Days Postpartum Source: Stevenson et al., 2003
Regulation of Anestrus
Hypothalamic Pituitary Axis (HP): Control Unit for Reproduction (Adapted from Senger, 2003).. Brain Hypothalamus Pituitary gland 36
General Physiological Mechanism for Anestrus : Hypothalamic Pituitary Axis (Adapted from Senger, 2003) Anestrus conditions Cycling condition LH 37
Basics of System: Cycling vs. Anestrus Metabolic Signals & Other CNS Signals + Ovary = active Hypothalamus GnRH Pulse Generator Ovary = quiet GnRH GnRH Anterior Pituitary LH pulse frequency LH pulse frequency 38
Lactation cow/calf bond Nutrition/BCS Bull Biostimulation Estradiol 17b + Metabolic Signals & Other CNS Signals Function of Hypothalamus GnRH pulse Generator Pregnancy & parturition Lactation cow/calf bond Nutrition/BCS Estradiol 17b High freq./low amp GnRH Low freq./high amp GnRH LH: High freq Low amp Pituitary LH secretion LH: Low freq high amp Normal Follicular Development/Estrus/Ovulation Ovary Anestrus/Anovulation Time after calving 39
Puberty Puberty is the occurrence of estrus and ovulation followed by the formation of a CL that leads to an estrous cycle of normal length. To MAXIMIZE fertility, heifers need to reach puberty by12-13 months of age.
Environmental Factors Nutrition Body composition? Season of birth Social cues: pheromone(s) Hormone therapy Stress (+, ) + Interactions, i.e., growth rate Metabolic Signals & Other CNS Signals Genetic Factors Breed Sire Heterosis (+, ) Puberty & Estrous cycles Ovary: follicular devel. maturation, ovulation LH pulse frequency Hypothalamus GnRH Pulse Generator GnRH GnRH Anterior Pituitary Peripuberal period Sensitivity to Estradiol Prepuberal anestrus Ovary: lack of follicular devel., maturation, ovulation LH pulse frequency 41
Depth of Puberty in Heifers Hormone Concentration Estrogen inhibitory! Prepuberty Increasing Depth of Anestrus Estrogen stimulatory! Peri- Puberty Progesterone -100-90 -80-70 -60-50 -40-30 -20-10 -5 0 5 10 15 20 Days Relative to First Estrus First Estrus
Summary Anestrus is the major factor regulating reproductive efficiency. Induction of estrus in anestrous cows is essential to maintaining a high reproductive rate. Estrus synchronization protocols for anestrous females MUST include a progestin (CIDR, MGA, or GnRH). Bottom Line: Adequate nutrition will solve a high percentage of anestrus problems both cows and heifers