Abnormal progesterone profiles as a sign of functional imbalance in the transition period. John M. Christensen 1 & Christina Ahm Petersen 2 1 Lattec I/S, Slangerupgade 69, 3400 Hillerød, Denmark 2 Lattec I/S, Slangerupgade 69, 3400 Hillerød, Denmark Abstract Automatic sampling of progesterone in milk provides knowledge about the functional status and the reproductive status. Additional to progesterone as a marker for the cows reproductive status the following exemplify an extra value of using continuously progesterone measurements in the open days period. The progesterone profile for each cow is compared to a reference profile and the number of abnormal profiles is used to state the herd s functional level as an example of how additional herd management information can be extracted from an indirect parameter. Abnormal is defined on the base of the profiles bottom length (inter-luteal interval), the profiles top length (luteal phase) and the cycle length. The data has been collected from four farms using automatic on-line sampling. Keyword: Christensen, Petersen, abnormal progesterone profiles, anoestrous, classification, commencement of first luteal activity, cycle length, functional imbalance, housing of dairy cows, inter-luteal interval, LH pulsation, luteinizing hormone. Introduction Progesterone is generally accepted as a valid parameter in the evaluation of individual cow s reproductive status (Horan 2005, Lamming 1998, Sartoni 2004). Progesterone, which is produced by the corpus luteum during the luteal phase, enables the division of the reproductive cycle into distinct phases based solely on this parameter. In figure 1 are some of these phases illustrated. 30 P4: ng/ml 25 20 LP = Luteal phase ILI = Inter-luteal interval 15 Profile 10 5 Anoestrous LP ILI 0 20 28 33 38 42 46 49 53 56 57 61 64 65 70 74 78 81 81 82 83 84 85 85 91 92 Figure 1: Some of the phases in the reproductive cycle DFC
Continuous progesterone measurements are commercially available and enable the creation of complete individual cow profiles. The magnitude of negative energy balance during the transition period is known to have a great impact on the reproductive performance of the individual cow in subsequent lactation; the greater the negative energy balance, the greater the negative effect on reproduction. In a review article by Growe et al (2008) about resumption of ovarian cyclicity it was reported that the key to optimize the resumption of ovulation is a body condition score of 2.75 3.0 at the time of calving and followed by a loss restricted to < 0.5 BCS units. The article states that Body condition score changes are good indicators of energy balance and reflect milk yield and dry matter intake. The same review article stated that development of the dominant follicle is dependent of the LH pulse frequency and in the final maturation stage is LH the key driver. It is reported by (Growe, 2008) that lower progesterone concentrations allow a slight increase in LH pulses than normal which allows for a prolonged growth of the dominant follicle. From the time of follicular deviation LH is the key driver in developing the follicle to the stage of ovulation. At the same time the release of progesterone from the corpus luteum end and begins again when a new corpus luteum has been formed after the ovulation. Traditionally, duration of anoestrus period is of primary focus when it comes to reproductive ability of the high producing dairy cow in the first 2-3 months of lactation. However, observations from Herd Navigator farms with reproductive challenges show that anoestrus period is not the only indicator of imbalance in the transition- and early lactation period. This imbalance may be of nutritional origin or be caused by external stressors in the period pre- and postpartum. Clear patterns in the occurrence of prolonged inter-luteal interval were observed; farms with a high proportion of cows with prolonged anoestrus also have a clear tendency of prolonged interluteal interval, despite a relatively low milk yield. Elevated estradiol metabolism and insufficient GnRH and LH pulsation is meant to be the primary reason for atreatia of the dominant follicle, causing delayed ovulation and prolonged interluteal intervals (Wiltbank 2011, Crowe 2008). Compromised GnRH and LH pulsation is also the believed to be the key to prolonged anoestrus. GnRH and LH pulsation may be affected by a number of factors i.e. negative energy balance or poor nutritional status and non-nutritional stressors like access to resources, quality of feed or hoof health in the period postpartum (Dobson 2000, Squires 2010). Abnormal progesterone profiles are considered normal in high-yielding dairy cows (Sartori 2004) and the abnormality is typically defined as prolonged anoestrus period, prolonged luteal period, prolonged inter-luteal period or formation of cysts, follicular or luteal. Evaluating individual progesterone profiles on herd level and assessing the number of abnormal profiles may prove to be a valid tool to indirectly evaluate herd management in the transition- and early lactation period. The objectives of this paper are to: (1) list possible explanations of causes behind abnormal progesterone profiles, (2) compare the progesterone profiles between known herds and (3) demonstrate a possible use of abnormal progesterone profiles as a sign of imbalance in the herd supported by use of visual observations in the individual herds. Materials and methods Empiric data were collected from herds with Herd Navigator (HN) automatic sampling, analyzing the progesterone content in the milk and detecting the heat. A cross sectional selection of the cows progesterone measures over a three month period has been used to identify abnormal progesterone profiles in terms of prolonged inter-luteal interval or prolonged luteal phase. The selected cows has not been divided in to pregnant or not pregnant
because it has been reported by (Gorzeka et al. 2011) that there is no clear difference in the progesterone profiles between pregnant and not pregnant dairy cows. The sampling pattern in HN after a heat is 5, 9 and 14 days from the heat detection date. If the progesterone level is less than 5 ng/ml at day 9 the system anticipates the cow is approaching a follicular cyst and changes the next sample to be day 12. A method to monitor the herd s inter-luteal interval (ILI) has been to define a classification model adapted to the HN s sampling pattern. The ILI is divided in to three classes: T1, T2 and T3, where progesterone first time is greater than 5 ng/ml either: T1 = before day 5 after heat detected, T2 = between day 6 and 9 after heat or T3 = between day 10 12 after heat. The class division is shown in figure 2. 30 P4: ng/ml 25 20 T1 T2 T3 15 Class T1 curve Class T2 curve 10 Class T3 curve 5 0-2 0 5 9 14 17 18 Figure 2: Division of the inter-luteal interval (ILI) in to three classes From a herd point of view all cows in the sampling window are classified and the size of each class is expressed in percentage. In order to find out if there is any difference between cows 60 days from calving and cows 100 days from calving, the cows were divided in to sub groups according to days from calving In earlier research reported by (Lamming et al. 1998) a typical oestrous cycle was defined by using progesterone measures and heat detection by experienced herdsmen. The cycles were defined to consist of sequences of luteal and inter-luteal intervals and the typical cycle had duration of a luteal interval of 13.4 days and an inter-luteal interval of 7.54 days. This definition is used to identify a herd with normal progesterone profiles. A method to state what the energy balance had been during the transition period and in the fertility period was to body score the cows in the fertility window (50 120 days from calving). The herds have been visited by the authors in November 2012 March 2013 in order to observe the barn environment, supply of nutrition and body conditioned score of the cows. The study has not looked in to uterine conditions such as retained fetal membranes, metritis or endometritis. Results and discussion Days from heat Continuous measurement of progesterone from day 20 post partum makes it possible to state when the first luteal activity has commenced in days from calving (DFC) in the herd. In figure 3 is the commencement of first luteal activity categorized in to five groups in steps of 20 days per category.
90 80 70 60 50 40 30 20 10 0 20-40 41-60 61-80 81-100 101+ Figure 3: Commencement of first luteal activity Herd 1 Herd 2 Herd 3 Herd 4 DFC Up to 80% of the cows in herd 1 had their first luteal activity before day 60 from calving and in herd 2 takes the majority of first luteal activity place in between 61 to 80 days from calving. In herd 3 and 4 are the first luteal activity spread between category 20 40, 41 60 and 61 80 days from calving. According to (Russell 2011) a prolongation of the anoestrous period is caused by a heavily negative energy balance. In today s loose housing systems is it difficult to follow the individual cow but by use of progesterone measurements the dairy farmer can get the individual cow picture back again and can make his management decision on that base. Another measure for reproduction performance is the cycle length. A split of the cycle in to inter-luteal interval and luteal phase gives new knowledge of what forms the cycle length. In figure 4 and 5 are the length of the luteal phase illustrated in relation to distance from parturition (DFC). 61-102 days from calving 103-144 days from calving 30.0 25.0 20.0 15.0 10.0 22.0 12.8 9.2 9.2 14.5 23.8 10.5 11.5 22.0 22.5 13.4 9.1 30.0 25.0 20.0 15.0 10.0 21.4 23.1 24.0 14.1 14.3 12.0 9.4 9.0 9.7 9.2 13.2 22.4 5.0 5.0 0.0 Herd 1 Herd 2 Herd 3 Herd 4 0.0 Herd 1 Herd 2 Herd 3 Herd 4 Inter luteal Luteal Phase Cycle length Figure 4: Luteal phase length, 61 102 DFC. Inter luteal Luteal Phase Cycle length Figure 5: Luteal phase length, 103 144 DFC. According to (Grove, 2008) are a prolonged luteal phase a sign of a prolonged growth of the dominating follicle. It is also derived from the data and combined with the visual observations in figure 8 that a well managed herd with a high yield has potential to a normal phase length defined by (Lamming et al. 1998). The analyze data in figure 5 shows that the luteal phase is not becoming shorter despite the cows have had to time to regain fertile capacity. Dividing the luteal-interval in to classes it becomes possible to see the distribution of cows within this batch of data. The result of the classification is shown in figure 6. In herd 2 classifies 41.7% in class T3. In herd 3 and 4 classifies respectively 63.0% and 73.4% in class 2. The classification shows also that in the well managed herd is it possible to impact the cows positively towards class 1 and meet the normal length defined by (Lamming et al. 1998). The classification results and the visual observations reflect each other. A comparison of the herds shows consistency in the data meaning that when the data shows abnormality it is also found in the field.
Herd 1 Herd 2 Herd 3 Herd 4 Number of cows 69 34 32 35 Total heats 134 65 63 82 Included heats 127 60 53 79 Days from heat T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 Distribution % % % % % % % % % % % % < 61 1.6 7.9 0.8 0.0 0.0 0.0 3.7 7.4 3.7 0.0 2.5 2.5 61-102 5.5 29.1 9.4 0.0 33.3 1.7 0.0 16.7 20.4 1.3 13.9 2.5 103-144 3.1 11.8 7.1 3.3 11.7 16.7 1.9 16.7 1.9 0.0 16.5 3.8 145-186 1.6 6.3 5.5 0.0 5.0 15.0 0.0 14.8 1.9 0.0 13.9 7.6 > 186 3.1 3.1 3.9 0.0 5.0 8.3 3.7 7.4 0.0 3.8 26.6 5.1 Total 15.0 58.3 26.8 3.3 55.0 41.7 9.3 63.0 27.8 5.1 73.4 21.5 Figure 6: Classification results distributed according to days from calving It is in figure 7 shown that 55.0 73.4% of the cows in the modern dairy herd s returns back to the luteal phase between day 5 and 9 from the end of the previous luteal phase. It is additional and with reference to earlier definitions of inter-luteal intervals (Lamming et al. 1998) derived from figure 7 that there are a potential to be captured. A combination of the information in figure 7 with the field observations in figure 8 points in the direction of improving the housing conditions, manage the negative energy balance better and avoid overstocking of cows in the time from calving to pregnancy have been achieved. 80.0 70.0 60.0 50.0 40.0 30.0 20.0 Herd 1 Herd 2 Herd 3 Herd 4 10.0 0.0 T1 T2 T3 Figure 7: Distribution of cows in to the three inter-luteal classes. One thing is to identify measures deviating negatively from normal and another thing is to know the causes behind the deviating measures the question is how does it look like in the real world? Are there conditions out there that favor an imbalanced herd? In order to answer the questions the herds were visited by the authors in November 2012 March 2013 to observe the barn environment, supply of nutrition and the body conditioned score of the cows. The result of the visual observations is shown in figure 8.
Visual observation Herd 1 Herd 2 Herd 3 Herd 4 Milk yield, > = greater than 10.000 kg; < = less than 10.000 kg > < < < Cubicle, brisket rail position, + = OK; - = not OK + - - - Cubicle, width, + = OK; - = not OK + - - - Silage quality, where +++ = excellent +++ ++ ++ ++ Cows per cubicle in the period from calving to conception 0.9 1.1 1.1 1 Cows per eating place in the period from calving to conception 0.9 1.1 1.1 1 Legs / hoof health, +++ = less then 10% with +++ ++ ++ ++ Dry cow management, where +++ = excellent +++ ++ + + Body Condtion Score, fertile period, 1-5 2.25 1.75 1.75 2 Stress score, where 0 = no stress and 1 = fight for space 0 0.8 0.5 0.4 Figure 8: Result of the visual observations It is from these observations derived that the on farm conditions corresponds with the results of the processed progesterone data. Herd 1 is well managed and the cows from this farm are used as a reference for normal progesterone profiles. The prolonged luteal phases and the majority of cows in class T2 and T3 inter-luteal intervals corresponds with the observation found in herd 2-4 Conclusions The abnormal progesterone profile in terms of a prolonged ILI can be used as a sign of imbalance in the herd, either impacted from the barn environment or from a negative influenced nutritional status. The hypothesis from the desktop examination of the data and visual observation of the progesterone profiles on the PC screen were meet when the real world were visited. It can be concluded that cows housed under sub optimal conditions will get a inter-luteal interval pointing in the direction of a length of up to 12 days. At the same time is the luteal phase prolonged with up to 2.6 days.
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