Gar-Lin Dairy Farms Inc. currently consists of 1,100 cows on 3X milking with 45 percent bST use. We have a 30,985 RHA with a 25 percent culling rate. All heifers and cows remain under our management and nutritional scheme. We grow our heifers on an accelerated growth program with an average age at calving of 23 months.

Since the onset of the modern era of biotechnology in 1973, scientists have made impressive strides in developing new agricultural biotechnologies. Biotechnologies that enhance productivity and productive efficiency (feed consumed per unit of output) have been developed and approved for commercial use. Technologies that improve productive efficiency will benefit both producers and consumers because feed provision constitutes a major component (about 70 percent) of farm expenditures.

[Today’s] distillers grains (DGS) tend to contain more protein, energy and available phosphorus than DGS from older ethanol plants, which likely reflects increased fermentation efficiency. Ethanol coproducts contain relatively high amounts of phosphorus, which can be a plus if additional phosphorus is needed in diets or a minus if excess phosphorus in manure needs to be disposed.

Dietary crude protein (CP) is an important determinant of milk production. Underfeeding CP is associated with reduced peak milk production. The partitioning of dietary CP into rumen degradable protein (RDP) and rumen undegradable protein (RUP) fractions has enabled a better understanding of protein utilization in the dairy cow. It has been recognized that feeding balances of RDP and RUP consistent with requirements for rumen microbial synthesis and milk production can improve nitrogen (N) utilization efficiency. In addition to improving milk production, providing sufficient balances of RDP and RUP may enhance fertility and reduce environmental losses of N. Protein and fertility In general, increasing CP in dairy rations has been associated with reduced fertility, measured by increases in services per conception (reduction in conception rate (CR)) or days open (a measure of reproductive efficiency). However, when studies were combined in a meta-analysis, CP had no association with CR, but excess of RDP above that needed for rumen microbial synthesis was associated with reduction in CR. Rumen requirement for RDP is largely determined by fermentable carbohydrate. NRC estimates the requirement of RDP as 1.18 times the yield of microbial crude protein, which is assumed to be 130 grams per kilogram (g/kg) total digestible nutrients (TDN) intake. This would equate to 24.5 g of degradable N per kg of TDN. Supplies of RDP providing more N per kg of TDN would increase rumen ammonia, plasma urea nitrogen (PUN) and milk urea nitrogen (MUN) concentrations. MUN and PUN are highly correlated; relative differences in MUN and PUN concentrations will depend upon time of sampling PUN relative to feeding and sampling of MUN from composite or a.m.-p.m. milk samples. MUN sampled from composite a.m.-p.m. milk samples tends to be a more stable estimate of MUN concentrations. Plasma and MUN will be used interchangeably in this [article]. Ferguson et al. observed that fertility in a dairy herd was sensitive to elevated PUN. During periods when diets were offered with elevations in RDP, which increased PUN, CR declined in the herd. Cows with PUN greater than 20 milligrams per deciliter (mg/dl) had CR under 25 percent. The data suggested that PUN concentrations above 20.8 mg/dl were detrimental to fertility. Canfield et al. associated elevated PUN with reduced CR in an experiment with higher dietary RDP. Several studies have examined increasing PUN or MUN and CR in dairy cows. A likelihood ratio test (LRT) for pregnancy was calculated for several of these studies. The LRT is calculated as the proportion of pregnant cows divided by the proportion of open cows within each urea category, as a proportion of the total cows. Pregnancy is more likely when the LRT is greater than one and less likely when below one. In general, as urea concentration increases in plasma or in milk, fertility declines. However, the decline in fertility is not uniform across the studies, and the highest fertility group in Godden et al. was in the highest MUN category. This suggests that there is a general trend in reduction in fertility with increasing MUN, but MUN alone does not predict fertility. Multiple factors influence fertility. Other risk factors for fertility, not identified in these studies, may modify the association of increasing urea on fertility in dairy cows. Westwood et al. found that cows consuming increased RDP had lower fertility when associated with greater weight loss in the early postpartum period, suggesting energy balance may play a modifying role on nitrogen effects on fertility. Other factors may include body condition loss, metritis and earlier days of first insemination. Melendez et al. found negative associations of increasing MUN with fertility in summer versus winter months. Cows may adapt to high urea levels and maintain fertility. Godden et al. found the relationship of fertility with urea was quadratic; fertility was higher in cows with low and high MUN concentrations. Gustafsson et al. observed a similar relationship in Swedish herds. Increased MUN is correlated with increased urinary urea. Urinary urea breaks down rapidly to ammonia when mixed with feces. Ammonia volatilizes rapidly from barn floors and contributes to air particulate matter and acid rain. Therefore, reducing MUN has other benefits[besides] reproduction. Together, the results suggest that fertility and environmental impact (and milk production) may be minimized when MUN concentrations are maintained between 9 to 16 mg/dl on a herd basis. Individual cow concentrations may range from 4 to 22 mg/dl, but the majority of animals will cluster between 9 to 16 mg/dl. Thus, high production can be supported with adequate protein and minimal urea concentrations. Mechanisms reducing fertility Specific actions by which increasing urea concentrations associated with excess RDP reduce fertility have not been identified. Effects may be associated with alterations in the uterine environment which are detrimental to the early embryo or effects may be detrimental to the oocyte, retarding development of the early blastocyst. Blanchard et al. observed embryo quality was reduced in cows consuming a 16.5 percent CP diet that contained 70 percent RDP compared with 62 percent RDP. The effect was not apparent in all cows, but particularly was seen in a higher proportion of cows in their 4th or greater parity. Approximately one-third of cows consuming the higher RDP diet failed to yield any fertilized embryos. Larson et al. found that cows with higher MUN had more failed pregnancies, which were associated with regular inter-estrous intervals, based on sequential milk progesterone testing. These data suggest higher RDP and urea concentrations are associated with fertilization failure as a cause of repeat breeding and should result in regular inter-estrous intervals. However, Elrod et al. observed that reduced fertility with increasing serum urea nitrogen in heifers was associated with increased inter-estrous interval and reduction in uterine pH early in the luteal phase. Infertility was associated with increased embryonic loss. Elrod’s work suggested that loss of embryos occurred after maternal recognition of pregnancy, which extended the inter-estrous interval, resulting in reduced fertility. These results are in contrast to Blanchard et al. and Larson et al. Blanchard and Larson’s studies were in lactating dairy cows, whereas Elrod’s studies were in primiparous, nonlactating cows. Therefore, mechanisms may be different. In addition, Blanchard’s study involved embryo’s collected from super-ovulated cows, seven days post-insemination, whereas Larson’s data was based on progesterone profiles post-insemination. Embryo loss prior to day 15 may have resulted in normal inter-estrous intervals in Larson’s study. Sinclair et al. found higher dietary RDP increased serum ammonia and effected oocyte maturation and early blastocyst development. McEvoy et al. observed that plasma ammonia concentrations measured at or near insemination in sheep were negatively correlated with pregnancy. These studies suggest that increases in serum ammonia may play a role in reducing reproductive performance in cows fed high RDP diets by influencing oocyte quality and blastocyst maturation. DeWit et al. and Ocon and Hansen found that oocytes incubated in increasing concentrations of urea had reduced proportions of fertilized oocytes that developed to blastocysts. DeWit et al. found that increasing urea was associated with reduced fertilization and cleavage rate, but had no effect on embryos after fertilization. Ocon and Hansen reported that fewer oocytes developed to blastocysts due to decreased developmental competence. Urea reduced fertilization and cleavage rate of developing embryos. Armstrong et al. found increased urea associated with increased nutrient supply decreased oocyte quality. However, Lavan et al. observed that Holstein cows fed diets high in rapidly rumen degradable nitrogen experienced no negative effects on follicular development or embryo growth despite increases in serum urea and ammonia, suggesting cows can adapt to short-term increases in RDP. Few studies have examined the relationship between RUP and fertility. Westwood et al. concluded that increasing RUP in isonitrogenous diets, improved feed intake, reduced serum nonesterified fatty acids postpartum and improved reproductive performance particularly in cows of high genetic merit. Triplett et al. fed a basal diet to postpartum beef cows with three supplements of increasing RUP (low RUP, 38.1 percent; moderate RUP, 56.3 percent and high RUP, 75.6 percent). Cows receiving the low RUP supplement had lower first-service CR than cows receiving the moderate and high RUP supplement (29.2 percent versus 57.6 percent and 54.6 percent, respectively). Overall pregnancy proportion tended to be lower for the cows receiving the low RUP supplement than the moderate and high supplements (43.2 percent, 61.5 percent and 56.4 percent, respectively). It is difficult to separate the effects of increasing RUP on fertility from the simultaneous reduction in RDP which occurred in these studies. Conclusion Risk factors which modify N effects on fertility have not been clearly identified. Although it seems fertility may be maintained at higher MUN concentrations, the general trend across the literature is a reduction in fertility. In addition, elevations in MUN are associated with increased urinary losses of N, a form of N which will be rapidly lost as ammonia to the environment. Nutritionists and veterinarians can monitor milk urea nitrogen (MUN) as a tool to assess efficiency of protein feeding. Mean MUN between 9.0 to 14 mg/dl is sufficient for adequate milk production and will ensure there are no negative effects on reproduction. Concentrations of MUN between 14 to 16 mg/dl should not significantly impair fertility but indicate some wastage of dietary N is occurring. MUN concentrations above 16 mg/dl not only may decrease fertility but also increase the risk of environmental pollution from ammonia volatilization. PD References omitted but are available upon request at editor@progressivedairy.com —From 2007 Mid-Atlantic Nutrition Conference Proceedings

The saying goes, “You can’t have your cake and eat it, too.” Sometimes we’re faced with the tough decision of choosing one action or the other rather than getting everything we want. Fortunately, when it comes to making money and keeping cows healthy on your dairy, things aren’t as complicated. You can have your tasty treat, by reaping more profits in your milk check, and savor it too, by ensuring rumen health and good protein nutrition for your herd.

Research and practical on-farm experience over the years has shown us that grouping cows according to age, nutritional needs and milk production at specific stages of the lactation can provide an economic benefit to many dairy farms. The dairy farmer who’s able and willing to group cows can do a more efficient and effective job of managing his herd. It opens the door for fine-tuning of feed rations, which has the potential to increase overall lactational performance and maximize income-over-feed-costs (IOFC) for individual groups. Properly formulated feed rations targeted for specific stages of lactation will result in a more productive and healthy cow.

“Hey, Doc, my cows are eating dirt. Waddya got for that?” A few years ago, I posed this question at several dairy seminars in the Midwest: “Do your animals chew on wood or eat dirt if they have the chance?” A few said their cows would chew on wood. Almost all indicated their cows would eat dirt, if available.

Nutritionist Terry Dvorachek is in expansion mode. That’s because his clients are, too. Within a few weeks, Mountain View Dairy in Luxemburg, Wisconsin, will open a new freestall barn and expand its herd from 600 to 1,100 cows. To prepare for the expansion, Dvorachek has been stretching out the dairy’s forages. “What I’m trying to do is keep tabs on the inventory of their feeds and look for feeds that would fit their feeding program,” Dvorachek says. That includes finding good nutrient profile matches for the dairy’s forages, such as soybean meal/canola meal to feed with its haylage and corn gluten feed for its silage. Pairing forage nutrient profiles with off-farm commodities amounts to what Dvorachek calls, “forage stretchers,” which help the dairy make the most of its available forages. “Don’t be afraid of buying products,” Dvorachek says. “Don’t be afraid to look at different products to buy to help address forage and energy needs.” Dvorachek currently feeds a ration that includes 38 percent corn silage and 18 percent haylage. To help make the dairy’s forages last longer and feed more cows this year, the ration has included ensiled peas and oats and Western baled hay. Both commodities have helped to “fill the gap” in meeting the growing dairy’s forage needs. After the expansion is complete, Dvorachek plans to transition the dairy to a ration that includes 55 or 60 percent silage. He says this will be possible because this fall more of the 400 acres owned by the dairy, where most of the dairy’s forages are grown, will be harvested in corn silage, which has a higher yield per acre than alfalfa or other crops. “In our area, we are becoming corn silage-driven,” Dvorachek says. “Our farms are getting larger, and producers just simply can’t produce enough haylage alone to feed their animals anymore.” As the percentage of corn silage in his rations have increased, Dvorachek says he’s also monitored fungus toxins. Within the last year, Dvorachek has found mycotoxins and aflatoxins creeping into silages. In turn, he has added a mycotoxin binder in Mountain View’s ration and in other dairy rations he consults in the area. “A lot of dairies are adding in a mycotoxin binder as a status quo ingredient,” Dvorachek says. “It’s an extra 12 cents per cow per day, but when you do the math, if you eliminate some abortions, how do you put a value on that?” To prepare for expansion, dairy owners, Mark and Al Seidl, had to overcrowd a few of their pens. It’s an added stress that Dvorachek says both he and the dairy’s owners have been “limping through.” To help minimize stress and competition at the feedbunk, Dvorachek says he’s focused on keeping the ration digestible, and he’s added extra minerals. Heat in late August and early September compounded stress and limited milk production in overcrowded pens, but Dvorachek says that minus the heat the ration and its added minerals have performed well and the cows have transitioned through the expansion process well. PD

Feed cost is the biggest concern for today’s dairy producers. The price of commodities such as cottonseed and soybeans, continues to drive up the cost of dairy rations.

In almost all biological systems, it is important that pH not deviate much from a fixed value. For example, for blood to carry oxygen from the lungs to tissue, pH must be maintained very close to 7.4. When rumen pH is either too high or too low, microbial fermentation and absorption of end products of that fermentation are less than optimal. Buffers, and other compounds, are added to rations for ruminant animals to aid in maintaining both blood and rumen pH in the desired ranges. What is pH? Maintenance of blood pH, in terms of animal survival, is extremely important. Supplying oxygen to tissues and temperature regulation are the only functions that take precedence over maintenance of proper acid-base balance. While it is extremely important to recognize this fact, the first part of this article will focus on the role of buffers in the digestive tract. The term pH is commonly used to describe the acidity or alkalinity of solutions. In regards to this discussion, the item of interest, however, is not pH, but what it represents, which is the concentration of hydrogen ions. Use of the term pH to describe acidity may be slightly confusing as it is not a numeric scale but a logarithmic scale. A change in rumen pH from 6.0 to 6.5 may appear to be slight, only 8 percent, but represents a 316 percent reduction in hydrogen ion (acid) concentration. What are buffers? Buffers are defined as compounds that resist change in the pH of a system. While rumen pH can vary dramatically, the normal range may be considered to be from 5.7 to 6.7. In this range, bicarbonate is the primary buffering system in the rumen, although there are other minor buffers as well. Bicarbonate, as a buffer, is most effective at a pH of 6.37 and is effective at a range of from 4.67 to 8.07. Commonly used compounds (such as sodium sesquicarbonate, potassium carbonate, sodium carbonate, magnesium oxide, calcium and magnesium carbonates) are more properly termed alkalizing agents based on their mode of action. Practically speaking however, this distinction only applies to magnesium oxide as all other compounds mentioned add to the rumen bicarbonate pool. A byproduct: Volatile fatty acids Volatile fatty acids formed during rumen fermentation are waste products produced by bacteria. Rumen fermentation is an anaerobic process and, as a result, conversion of carbohydrates in feed to microbial cells is greatly exceeded by the amount of these various waste products. When these waste products are absorbed and utilized by the host animal, the amount of energy to provide for cell maintenance and growth greatly exceeds that available to rumen bacteria. Most common among the volatile fatty acids produced during fermentation are acetic acid, propionic acid and butyric acid. It has been estimated that if the rumen were not buffered, the pH may drop to approximately 3.0. Dissociation constants vary for common volatile fatty acids. This means that not all acids produced during rumen fermentation produce the same level of acidity. If propionic acid has a relative rank of 1.0, then butyric acid and acetic acid are 1.09 and 1.30, respectively. Lactic acid, found in silage and produced in relatively large quantities when animals are not well adapted to high-grain rations, is much more acidic than the volatile fatty acids. Lactic acid is 10.3 times more acidic than propionic acid, which can lead to problems when animals consume large amounts of silage. None of these organic acids can compare to hydrochloric acid, which is more than 70,000 times as strong an acid as propionate. Neutralizing acid Buffers also vary in their ability to neutralize or completely consume acid. Based solely on chemistry, one can rank buffers on a scale of from one to 10, 10 being the best. Table 1 shows a comparison of theoretical acid-consuming capacity and measured acid-consuming capacity. It should be noted that while magnesium and calcium compounds rank higher than sodium and potassium compounds, there is much more variability in quality for the former. Some calcium and magnesium buffers and alkalizing agents are relatively poor acid consumers, while others are quite good. Generally speaking, these are unrefined products and can vary based on the particular deposit from which they are mined. Potassium and sodium buffers and alkalizing agents are usually refined products and, as such, are more consistent in performance. Unrefined trona ore, predominantly sodium sesquicarbonate, tends to be less variable in performance than mined calcium or magnesium products. In general, products should be chosen based on consistency of measured results. Quantities of buffers added to rations depends on a number of factors: rate and extent of rumen carbohydrate fermentation, quality and quantity of fermented feeds (such as corn silage) and passage rate are some of the most important. It is possible to calculate the amount of buffering required if ration composition and kinetics of rumen degradation are known. Plant cell walls and starch are carbohydrates varying dramatically in rate and extent of rumen degradation. If one assumes rumen losses of plant cell walls are 40 percent, then for a cow consuming 50 pounds of dry matter (DM) with 28 percent plant cell walls, theoretical production of acetic acid, propionic acid and butyric acid from cell wall fermentation are 2.0, .90 and .80 pounds, respectively. Bacterial waste, as volatile fatty acids, are 3.7 pounds and .65 pounds of microbial cells are produced from 14 pounds of cell walls. If the same ration contained 35 percent starch and that starch was 90 percent fermented in the rumen, theoretical production from that portion of the feed yields 10.5 pounds of volatile fatty acid and about 2.0 pounds of microbial cells. Rations higher in fiber require less acid neutralization partly because of higher salivary secretions and lower rates of acid production. Feed fiber, especially that found in legumes, can remove acid much in the same way a water softener removes calcium from water (ion exchange). Total ion exchange capacity of most rations is limited; the equivalent of a fraction of an ounce of sodium bicarbonate. Amounts of buffers added to the ration can be calculated based on ruminal acid production, salivary bicarbonate production and feed pH. Excessive acid neutralization can be as deleterious as insufficient buffering, as dissociated volatile fatty acids are not absorbed as well as undissociated volatile fatty acids. When rumen pH rises too high, absorption of volatile fatty acids across the rumen wall ceases, as will rumen fermentation. At a pH of 6.0, approximately 95 percent of acetic acid is dissociated, as are 93 percent of both propionic and butyric acids. It is interesting to note that volatile fatty acid absorption across the rumen wall is more rapid shortly after a meal, before salivary secretion increases. Since estimates regarding production of volatile fatty acids and microbial cells have been made, a brief (unrelated to buffers) yet important discussion follows. Plant cell walls are important in overall rumen function; however, the role of rumen fermentable starch cannot be overemphasized. As can be seen from the previous example, the contribution of starch fermentation to microbial cell growth is much greater than plant cell wall fermentation. At amounts that might be found in a typical dairy ration, starch has the potential to grow three times the amount of microbes and nearly five times the amount of propionic acid as plant cell walls. The implications of this, as regards milk production, are clear. Regulating blood pH While rumen pH can vary over a broad range, blood pH does not. Under conditions commonly found in the rumen, acid content, as measured by pH, can vary 10 fold. Blood acid content is highly regulated and varies by no more than 10 percent from the average. Normal blood pH is 7.4; animals are alkalotic when pH is greater than 7.45 and acidotic when pH is less than 7.35. Metabolism must be altered to correct either condition as blood pH outside the range of from 6.8 to 7.8 results in death. Regulation of blood pH is not as simple as the situation in the rumen. Hydrogen ions (acid) in blood are positively charged and in order to maintain a zero charge, one of two events must occur. Introduction of acid (positively charged) must be accompanied by the addition of a negatively charged ion (anion) such as chloride or bicarbonate, or the loss of positively charged ions (cations), such as sodium or potassium. Potassium, sodium and chloride are classified as dietary fixed ions; they are quantitatively absorbed from the gut, are not metabolized and excesses are excreted in urine. Combustion of feed indicates effects on acid-base balance; ash from cereal grains is acid, while that from forages is alkaline. Cattle are much more tolerant of alkalosis than acidosis and, as such, require a slight dietary excess of positively charged fixed ions. The magnitude of this excess is determined by a number of factors including metabolic state. Growth is a state when animals are in a negative acid balance; while catabolic states, such as starvation, represent a positive acid state. Acid-base imbalance affects multiple metabolic processes; among these are impaired glucose metabolism and transport of compounds across cell membranes. Ultimately, under prolonged conditions of acid-base imbalance, animal health and efficiency are reduced. Modern management practices increase energy density to improve production, primarily with increased intake of cereal grains. Until recently, no attention was paid to acid-base balance in cattle. It has been suggested that benefits resulting from the addition of buffers, such as sodium bicarbonate, relate as much to fixed ion addition (sodium) as to acid neutralization. Sodium, potassium, chloride, phosphorus, sulfur, calcium and magnesium are commonly included in equations describing dietary acid-base status. Phosphorus, sulfur, calcium and magnesium may warrant inclusion occasionally, but these are typically added to rations to satisfy requirements. Unlike sodium, potassium and chloride, absorption of phosphorus, sulfur, calcium and magnesium is variable and often low. Sulfur is a constituent of several amino acids, and as such, metabolic state influences the contribution of sulfur to acid-base balance. Equations describing dietary fixed ion differences must be predictive of acid-base balance across all metabolic states. In addition, the simplest equation describing a system is to be used in preference to a more complex one that does not increase accuracy of prediction. Summary Regulation of acid-base balance in ruminants is a more complex system than that in non-ruminants. To meet the demands of high production, feeds are included in rations that can disrupt ruminal and metabolic processes. Buffers are added to rations to mitigate negative effects of acids produced during fermentation on rumen health and function. Additionally, buffers allow blood pH to remain in a range that maximizes performance and animal health. PD References omitted but are available upon request at editor@progressivedairy.com