Reproductive Management -

Reproductive Management - A Nutritionist=s Perspective

University of Missouri - Columbia, S134 Animal Sciences Unit, Columbia, MO 65211, U.S.A.

Take Home Messages

Nutrition management influences reproduction in the dairy cow.

Dry cow nutrition must be carefully managed to prevent metabolic diseases that can adversely affect reproductive performance of the dairy herd.

Energy balance during early lactation is the second key nutritional factor that affects reproduction.

Protein, vitamins and minerals must also be balanced to support optimal reproductive function of the lactating dairy cow.

Introduction

The concept of setting goals and time constraints is not new in business management. But how does it apply to dairy farm management? In evaluating the production cycle of the dairy herd, a 100 day period of critical importance exists. The 100 day contract begins 30 days before calving and runs through first breeding at 70 days after calving. The terms of the contract include: birth of a live calf with the cow remaining healthy during the transition period; a high peak milk production; controlled loss of body condition; and high fertility at first breeding. The momentum of achieving success begins in the close-up dry cow group and builds through calving to first breeding. Getting the cow off the track disrupts the momentum and can lead to Awrecks. Wrecks include metabolic disorders during the periparturient period that can have a long term impact on production and reproduction. This paper will focus on a phase by phase look at the A contract and the long-term consequences of cows getting off track.

The Dry Cow

The contract begins with the care and preparation of the prepartum dry cow. The idea of preparing the dry cow is different from the traditional role that considers the dry period a Arest@ phase (Gerloff, 1988). The cow needs to be prepared for calving and initiation of lactation. Although not producing milk, the pregnant, prepartum cow is very metabolically active both reproductively and in establishing new mammary growth. Bell and coworkers (1995) measured energy and protein deposition in the uterus and fetus. Their research clearly illustrates the increased nutrient requirements during the final 30 days of gestation (Table 1).

Table 1. Rates of energy and protein deposition in uterus and fetus during pregnancy in Holsteins.

Gestation (d)	Energy (Kcal/d)		Protein (g/d)
Gestation (d)	Uterus	Fetus	Uterus	Fetus
210	631	500	76	54
230	694	601	90	73
250	757	703	103	91
270	821	805	117	110

Adapted from Bell et al. (1995).

During this same time period, there is a rapid development of the mammary gland and initiation of lactation. In short, there is a significant increase in metabolism of the cow during the final 30 days of gestation and therefore a need to maintain intake and proper plane of nutrition.

Dry matter intake is also altered with feed intake decreasing during the last 2 weeks of the dry period. Dry matter intake has been shown to decline by as much as 30 to 40% from 2% to less that 1.5% of the animals= body weight. Lower feed intake results in a negative energy status and mobilization of fat and protein. Depressed feed intake puts the animal at risk for a number of metabolic disorders.

# Parturition Disease Complex

Severe losses of body stores or a more general lack of properly balanced nutrients increase the risk of the animal experiencing a number of metabolic diseases. Markusfeld (1993) describes these as a parturition disease complex. This is an important concept in understanding that these disorders are not independent but are related (Figure 1). As shown in the illustration, a cow suffering from milk fever is at increased risk of having retained placenta, left displaced abomasum, and/or ketosis. A number of other interactions exist between preparturient diseases.

Stillbirth

Prolapse

Milk Fever

Metritis

Retained Placenta

Acidosis

LDA

Ketosis

Grohn and coworkers recently reported the incidence of these diseases for Holstein cows in New York (1995). Values are reported in Table 2.

Table 2. Lactational incidence risks and median days postpartum of disorders in 8070 multiparous Holstein cows in New York state.

Disorder	Lactational Incidence Risk, %	Median Day of Occurrence, d
Retained placenta	7.4	1
Metritis	7.6	11
Ovarian Cyst	9.1	97
Milk Fever	1.6	1
Ketosis	4.6	8
Displaced Abomasum	6.3	11
Mastitis	9.7	59

Grohn et al. (1995)

As the median day of occurrence indicates, these diseases are most likely to occur during the time immediately after calving. However, these disorders will impact production and reproduction during the entire lactation.

# Reproduction Calving

The culmination of these disorders is lost production and income. Markusfeld reported significant decreases in milk production and reproductive performance of cows suffering from postparturient uterine (PPU) disease (Table 3).

Table 3. Losses due to postparturient uterine diseases ¹

	Milk lb/305d	Days Open
With PPU disease	19,677	125
Without PPU disease	21,978	99
Difference	+ 2,121	- 26

^{1 Adapted from Markusfeld (1993).
Decreased milk production and reduced reproduction efficiency are the typical losses associated with periparturient diseases. Therefore, the incidence of these diseases must be closely monitored. Retained placenta and related reproductive tract infections are often described as being due to nutrition deficiencies. More specifically, since researchers at Ohio State University reported the relationship between Vitamin E, selenium and retained placenta, many producers first react to cows calving with retained placenta by increasing vitamin and mineral supplementation of the dry cow diet. Correct vitamin and mineral supplementation is certainly a goal of properly managing the transition cow. French researchers, however, more completely described retained placenta as an under-nutrition disease. Chassagne and Chacornac (1993) reported cows that experienced retained placenta were on a lower plane of nutrition. Blood metabolites measured showed higher fat mobilization and lower blood glucose, as well as lower blood calcium and amino acids (Table 4). In addition, cows with retained placenta also had lower circulating monocytes.
Table 4. Measurements of blood metabolites and nutrients between normal cows and cows with retained placenta.}

Item	Retained	Normal
Glucose, ng/100 m	59.6	61.8
NEFA, meq/d	.494	.340 **
Amino Acids, mnole/d	2.34	2.48 **
Calcium, mg/d	96.3	98.5 **
Monocytes, 10³/mm³	225	310 **

** P < .05

These results emphasize the importance of the overall plane of nutrition. A common nutritional limitation is the quality of the forage selected for feeding the dry cow herd. In addition, the feeding management system often fails to promote feed intake of the dry cow herd. Lower plane of nutrition results in excessive body weight losses and can disrupt energy metabolism.

Grohn and others determined that ketosis was an important metabolic disorder compared to other diseases. Ketosis is related to disrupted energy metabolism. Simensen and coworkers (1990) reported peak levels of ketones in milk at 17 to 31 days after calving. There was a significant relationship to milk yield with increasing acetoacetate (a ketone) in the milk. As acetoacetate increased to levels > .1 nnol per liter of milk, there was a significant decrease in milk production. Therefore, it has been established that early lactation cows suffering from ketosis have lower milk production.

Although not reported as often as other calving disorders, milk fever is a significant risk factor for several other disorders including retained placenta and displaced abomasum. Subclinical milk fever and/or ketosis or a combination of the two can directly contribute to successfully accomplishing the A100 day contract@. Cornell researchers reported increased incidence of milk fever as lactation number and genetic potential increased. These same researchers cited studies that showed decreased productive life by 3.4 years. Given that older, higher producing cows are most susceptible to these disorders, the economic impact of parturient paresis can be significant in lost production but also loss due to premature culling.

The concern of disrupted metabolism caused by ketosis and milk fever is the increased risk of other periparturient diseases. Curtis and coworkers (1983) reported milk fever resulted in significant increases in other transition cow problems. As illustrated in Table 5, milk fever led to increased risk of dystocia, retained placenta, left displaced abomasum, ketosis and mastitis.

Table 5. Influence of hypocalcemia on risk of other perparturient disorders. ¹

Disease	Odds Ratio	P
Dystocia	2.8	< .0001
Retained placenta	6.5	< .0001
Left displaced abomasum	3.4	< .06
Ketosis	8.9	.0001
Mastitis	8.1	.0001

^{1 Adapted from Curtis et al. (1983).
Based on review of the literature, Coppock (1974) concluded that factors which caused loss of muscle tone (atony) increased risk of Displaced Abomasum (DA). These results were supported by a more current report by Massey and others who found milk fever increased risk of DA 4.8 times.
The often overlooked aspect of DA was the increased risk with increased stress of parturition. Other factors that Coppock identified as risk factors included toxemia due to metritis and mastitis. Although the DA can be repaired surgically, cows have reduced milk production of 8 to 10 percent compared to normal cows in the same herd.}

# Early Postpartum Cows

Metabolic disorders and diseases and the prevention of those problems are critical to successfully reaching the 100 day contract. The second phase is to achieve peak milk and good fertility at first service. Miettinen (1990) reported cows with higher levels of ketone bodies (acetoacetate and beta-hydroxybutyrate) had increased days to first service, decreased pregnancy rate at first service and as a result, a longer days open with higher services per conception (Table 6).

Table 6. The effects of early postpartum energy status on reproductive performance. ¹

	Days to First Service	Days Open	S.C.	First Service Concept. Rate, %
Normal	70.5	80	1.2	75
Subclinical Ketosis	75.8	102	2.0	44
Ketotic	78.0	100	1.9	40

^{1 Adapted from Miettinen
The results of the study from Finland illustrate the importance of minimizing metabolic disorders on reproductive efficiency.}

A common denominator of the periparturient diseases discussed above is a reduced plane of nutrition. This poor level of nutrition is directly related to intake and energy balance. Energy balance during the periparturient impacts on reproduction. Butler and coworkers reported the energy balance during the first 20 days was inversely related to days to normal ovulation. These researchers also noted that normal ovarian function was observed 10 days after energy balance reached its lowest point and began to return to a positive balance. Lucy and others reported similar results with increased number of larger follicles present as estimated energy balance increased. Another concern is the carryover effect of negative energy balance on fertility. Britt from N.C. State has proposed a period of negative energy balance influences the development and quality of pre-ovulatory follicles. In this case, cows experiencing severe body condition loss in the last weeks of gestation and/or early lactation will have reduced conception rates. Poor fertility would be due to an Aimprinting@ of ovulatory follicles during development and recruitment of these oocytes.

# Protein Nutrition and Reproduction

While the relationship between energy balance and reproduction has become better understood, the effect of protein nutrition on reproductive efficiency is less clear. During the last several years, the Degradable Protein System has been adopted for diet formulation for growing and lactating dairy cattle. The objective of this system is to provide sufficient soluble/degradable protein to maximize rumen microbial fermentation and growth with undegraded intake protein supplying amino acids to the small intestine above microbial supply. This balance of protein types would prevent excess ammonia production in the rumen which would lead to elevated blood urea nitrogen (BUN) levels. Several reports suggest increased BUN levels would cause increased levels of urea/ammonia in reproductive tract secretions. These nitrogen compounds could result in decreased viability of the sperm cells, ovulated egg and the embryo itself. Decreased fertility would result with increased services:conception and days open. serum urea level in excess of 20 mg per dl has been reported as a means of evaluating degradable:undegradable protein balance in lactating cows. This figure must be used with caution as undegradable intake protein supplied in excess of the animals requirements will ultimately be processed to urea.

Research evaluating protein nutrition and reproductive performance is confounded with energy status of the animal. Higher protein diets will generally elicit a milk production response resulting in a more negative energy balance. Conversion of ammonia to urea by liver tissue also requires energy. In a number of the research trials, diets were reformulated by removing cereal grains and increasing degradable protein. This change in itself could influence energy balance of the cow.

# Managing Protein Balance

Guidelines for the proper balance of protein types are influenced for the types of feedstuffs and forages being fed. In general, 60 to 65 percent of the dietary crude protein should be degradable crude protein. Of the degradable protein, 40 to 60 percent should be soluble crude protein. Thirty-five to forty percent of the diet protein should be undegradable intake. Although it is unclear if imbalances will adversely affect reproductive efficiency of dairy cows, properly balanced protein components of the diet will enhance production, improve efficiency and minimize incidence of increased blood nitrogen levels.

# Minerals, Vitamins and Reproduction

Balancing energy and protein are critical in achieving maximum production. Micronutrients, minerals and vitamins, are also important in achieving efficiency and profitable levels of production. Several minerals and the fat soluble vitamins have been associated with reproductive performance. Of the macrominerals, calcium and phosphorus ratios and intake are extremely important in preventing milk fever at calving. Cows suffering from milk fever are more prone to retained fetal membranes, prolapsed uterus and metritis. Therefore, dry cow nutrition management is important in prevention of these disorders. Should a herd develop milk fever problems, calcium intake should be evaluated. Calcium intake should be limited to less than 75 g per cow per day. Phosphorus should be kept in 1:5:1 ratio to calcium intake. In the event milk fever problems continue, anionic salts can be used as an additional aid for the prevention of milk fever. Anionic salt packs should be used after calcium intake has been controlled without success in controlling milk fever.

Two microminerals associated with enhancing reproductive performance are zinc and selenium. Zinc=s role in reproduction is not well defined but several roles may exist. Zinc supports tissue healing and restructuring that may be important in post-partum uterine healing. Zinc is also a component of enzyme systems that could influence hormonal profiles during pregnancy. Selenium=s role in reproduction has been more closely evaluated. A recent review of published reports indicated Se and Vitamin E supplementation decreased the incidence of retained placenta, metritis and increased the rate of uterine involution. Vitamin E and selenium reduce tissue damage and function to maintain tissue integrity. This role of these micronutrients could enhance the uterine environment and support increased fertility.

# Managing Minerals and Vitamins

Minerals and vitamins are added in small quantities, but it is essential that they are provided in adequate amounts to meet the animals needs. Calcium and phosphorus intake should be controlled in the prepartum transition diet to less than 75 g of calcium with phosphorus maintained at 1:5:1 ratio to calcium. Zinc, selenium, Vitamin E and all other micronutrients should be balanced to meet but not exceed recommended levels. In some cases, additional vitamin E and selenium have been used in problem herds. However, extreme care must be used to control intake.

# Feeding System Considerations

Nutritional management is critical to achieving peak milk production to genetic potential. In doing this, many nutrition programs are designed to Alead feed@ or Achallenge feed@ the fresh cow immediately after calving. In fact, many producers begin to accelerate grain feeding during the prepartum cow preparation program. While the concept of this approach is correct, the implementation must be accomplished carefully. Excessive grain feeding can lead to ruminal acidosis. Ruminal acidosis decreases dry matter intake and can predispose cows to other periparturient diseases. Acidosis can also result in laminitis in cattle (Vermunt and Greenough, 1994). These scientists report systemic infections can contribute to laminitis. For example, cows with severe metritis can develop laminitis in response to the systemic disease. Poor locomotion due to sore feet can result in significantly lower milk production. The largest incidence of lameness reportedly occurs during the first 50 to 70 days after calving, the period of peak milk production (Collick et al., 1989). Lameness also resulted in a significant increase in days to first service, days open and services per conception. The result of over compensating with grain can actually be higher cull rates due to lowered milk yield and poor reproductive performance due to sore feet.

# Summary

Management of the A100 day contract@ is a series of delicate negotiations for the dairy farm management. Failure at any point increases the risk of failure of making a smooth transition and to meet the terms of the deal. The stress of calving must be intensively managed to reduce the odds of periparturient disease and increasing the odds of success. Details and intake are the key elements of the A100 day contract@.

# References

Bell, A.W., R. Slepetio and R.A. Ehrhardt. 1995. Growth and accretion of energy and protein in the gravid uterus during late pregnancy in Holstein cows. J. Dairy Sci. 78:1954.

Butler, W.R., R.W. Everett and C.E. Coppock. 1981. The relationship between energy balance, milk production and ovulation in postpartum Holstein cows. J. Animal Sci. 53:742.

Collick, D.W., W.R. Ward and H. Dobson. 1989. Associations between types of lameness and fertility. Vet. Record 125:103.

Coppock, C.E. 1974. Displaced abomasum in dairy cattle:Etiological factors. J. Dairy Sci. 57:926.

Curtis, C.R., H.N. Erb, C.J. Sniffen and R.D. Smith. 1984. Epidemiology of parturient paresis:predisposing factors with emphasis on dry cow feeding and management. J. Dairy Sci. 67:817.

Curtis, C.R. et. Al 1983. Association of parturient hypocalcemia with eight periparturient disorders in Holstein cows. J. Am. Vet. Med. Assoc. 5:559.

Gerloff, B.J. 1988. Feeding the dry cow to avoid metabolic disease. Vet. Clinics of N. Amer.:Food An. Pract. 4(2):379.

Grohn, Y.T., S.W. Eicken and J.A. Herth. 1995. The association between previous 305 day milk yield and disease in New York state dairy cows.

Lucy, M.C., C.R. Styples, F.M. Michel and W.W. Thatcher. 1991. Energy balance and size and number of ovarian follicles detected by ultrasonography in early postpartum dairy cows. J. Dairy Sci. 74:473.

Markusfeld, O. 1993. Parturition disease complex of the high-yielding dairy cow. Acta Vet. Scand. Suppl. 89:9.

Massey, C.D., C. Wong, G.A. Donovon and D.K. Beade. 1993. Hypocalcemia at parturition as a risk factor for left displacement of the abomasum in dairy cows . J. Am. Vet. Med. Assoc. 6:852.

Miettinen, P.V.A. 1990. Metabolic balance and reproductive performance in Finnish dairy cows. J. Vet. Med. A37:417.

Simensen, E., K. Halse, P. Gillund and P. Lutnaes. 1990. Ketosis treatment and milk yield in dairy cows related to milk acetoacetate levels. Acta Vet. Scand. 31:443.

Vermunt, J.J. and P.R. Greenough. 1994. Predisposing factors of laminitis in cattle. Br. Vet. J. 150:151.