Cow Talk with an Expert: Mastitis Treatments

 

Pam Ruegg-3036

Risks, Realities and Responsibilities Associated with Mastitis Treatments

Pamela L. Ruegg
University of Wisconsin,
Madison, Wisconsin, USA

Introduction
Mastitis remains the most common disease of dairy cows and treatment or prevention of this disease is the most common reason that antibiotics are administered to cows (Pol and Ruegg, 2007, Saini et al., 2012). Mastitis is detected by inflammation that is caused by infection by microorganisms and occurs in both clinical and subclinical forms. Milk obtained from quarters of cows with subclinical mastitis looks normal (even when millions of somatic cells are present) but the milk contains an excessive number of somatic cells, (with or without the detectable presence of pathogenic organisms) (Dohoo and Leslie, 1991). Unless the herd prevalence of subclinical mastitis is high, subclinical infections are usually managed by antimicrobial treatments administered at the end of the lactating period. Inflammation that results in visible abnormalities of milk or the gland is defined as clinical mastitis. Most symptoms of clinical mastitis are quite mild and cannot be detected unless foremilk is observed, thus the perceived incidence of clinical mastitis on individual dairy farms is dependent on the intensity of detection. In a study that enrolled almost 800 cases of clinical mastitis occurring on 50 Wisconsin dairy farms, 50% of clinical cases presented with only abnormal milk, 35% of cases had abnormal milk accompanied by swelling of the affected quarter and only 15% of clinical cases presented with systemic symptoms (Oliveira et al. 2013). In most countries, milk from cows affected with clinical mastitis cannot be sold for human consumption and most farmers administer antimicrobials to affected cows. The use of antimicrobials to treat food animals is under increased scrutiny by consumers, governmental officials and regulatory agencies and must be well justified. The purpose of this paper is to review the risks, realities and responsibilities associated with treatment of clinical mastitis.

Realities of Mastitis Treatments on Modern Dairy Farms
Widespread adoption of the 5-point plan (Neave et al., 1969) has been demonstrated to successfully control contagious mastitis pathogens. As a result, in many developed dairy farm regions, the prevalence of mastitis caused by Staphylococcus aureus is minimal and Streptococcus agalactiae is virtually eradicated (Table 1; Makovec and Ruegg, 2003; Pitkala et al, 2004). As contagious pathogens have been controlled and herds have adopted intensive management practices, clinical mastitis is caused by an increasingly diverse group of opportunistic pathogens (Table 1). Knowledge of these changes in etiology is important because the pathogenesis, virulence and prognosis of clinical mastitis are influenced by important characteristics that vary among pathogens. Depending on specific virulence factors, organisms infect different locations within the mammary gland, have differing abilities to cause systemic symptoms, vary in the expected duration of subclinical phases of infection and differ in the expected rate of spontaneous bacteriological cure. For example, expectations for spontaneous bacteriological cure of subclinical and clinical mastitis caused by Staph aureus are essentially zero(Oliver et al., 2004) while the expectation for spontaneous cure of E coli is quite high (Suojala, 2010) and therapeutic cure rates for several pathogens (yeasts, pseudomonas, mycoplasma, prototheca etc.) are essentially zero, regardless of treatment.

Table 1.  Results of selected studies that describe the distribution of bacteria recovered from milk of cows with clinical mastitis in modern dairy herds located in developed countries (Table adapted from Ruegg et al., 2014).

Country Herds Milk Samplesa S. aureus Other staph Strep agalactiae Other strep Coliform Other No Growth
Holland (de Haas, 2002) 274 2,737 18% 6% 0% 25% 28% NRb 22%
UK (Bradley, 2007) 90 480 3% 13% 0% 25% 21% 11% 27%
New Zealand(McDougall, 2007) 28 1,332 19% 7% 0% 45% NR 4% 27%
Canada(Olde Riekerink, 2007) 106 2,850 11% 6% 0% 16% 15% 5% 47%
USA(Oliveira, 2013) 50 741 3% 7% 0% 11% 36% 16% 27%

aResults characterized as contaminated and mixed infections were excluded;  bNR indicates that the study did not report that outcome

More than 80% of cases of clinical mastitis present solely with local symptoms (Oliveira et al., 2013, Oliveira and Ruegg, 2014) and in the U.S. (Richert et al., 2013) (and a number of other countries), very few cases are examined or treated by veterinarians.   In many regions, intramammary (IMM) antimicrobial therapy is the usual treatment for mild and moderate cases of bovine mastitis and most cases are treated by farm personnel without determination of etiology (Hoe and Ruegg, 2006; Oliviera and Ruegg., 2014).   In spite of considerable changes in the etiology of mastitis, there has been limited innovation in development of mastitis therapies and there is relatively little variation in the types of treatments that are administered. While different countries have various combinations and routes of allowable drugs, most products are β-lactams.

In many countries, almost all approved IMM antimicrobials havelabel indications primarily for treatment of Streptococci and Staphylococci. In the U.S., there are no approved IMM products for treatment of cases caused by Klebsiella spp. nor for many other pathogens that account for most cases of clinical mastitis. In the U.S., 88% of cases of clinical mastitis occurring in 51 larger WI dairy herds received 1st (16%) or 3rd (72%) generation cephalosporin (Oliveira and Ruegg, 2014). About, 35% of these treatments were given to cases which were culture negative at the time of detection and a further 17% were administered to cases for which there are no approved effective antimicrobials. The probability of cure is highly influenced by the characteristics of the pathogen.

In the United States, only two antimicrobial classes are represented among commercially available IMM products that are approved by the U.S. Food and Drug Administration (FDA). Those classes include 6 or 7 commercially available IMM products that contain β-lactams (amoxicillin, ceftiofur, cephapirin, cloxicillin, hetacillin, and penicillin) and 1 product that contains a lincosamide (pirlimycin).   While several products have been withdrawn from the U.S. market, no new antimicrobials have been approved for mastitis therapy since 2006.

In the U.S., there are no antimicrobials that are labeled for systemic treatment of mastitis, however extra label usage of some compounds is allowed under veterinary supervision. Of 589 cows treated for mastitis on 51 Wisconsin dairy farms in 2012, 66% received solely IMM therapy, 1% received solely systemic therapy, 16% received IMM and systemic therapy, 14% received secondary treatments via either IMM or systemic routes and 18% received supportive therapy (Oliveira and Ruegg, 2014). The majority of systemic treatments were for cases of severe mastitis and most of the antimicrobials used would not be expected to reach therapeutic concentrations in mammary gland tissue. As most treatments are administered simply based on observation of inflammation without determination of etiology, many treatments are difficult to justify both medically and to consumers. Of 585 cases that had a microbiological diagnosis, the most common treatment was use of IMM ceftiofur for treatment of microbiologically negative cases (23% of all treatments) (Oliveira and Ruegg, 2014). Based on the etiologies, case severity and available treatments, only about 35% of the antimicrobial usage can be justified based on the availability of scientific data that demonstrates a benefit of using an IMM antimicrobial (Table 2).

Table 2. Distribution of etiologies, availability of data that demonstrates benefit of use of IMM antimicrobials and proposed antimicrobial treatments for 690 cases of clinical mastitis occurring on 51 Wisconsin dairy herds.

Etiology of Case Severity of Case Cases (n) (%) Data demonstrating benefit of IMM antimicrobials Proposed antimicrobial Treatment
E coli Severe 76 11% No Systemic
E coli Mild & mod. 114 17% No Nonea
Klebsiella sp All 36 5% No IMM (mild/mod) & systemic (severe)
Enterobacter sp All 19 3% No None (mild/mod) or systemic (severe)
Strep spp. All 91 13% Yes Extended duration IMM
Enterococci spp Mild & mod. 15 2% No unknown
CNS Mild & mod. 43 6% Yes Short duration IMM
No Growth Mild & mod. 203 29% No None
Yeast Mild & mod. 23 3% No None
Staph aureus All 23 3% In some cases Yes Cull cow or dry quarter
Truperella pyo. Mild & mod. 15 2% No Cull cow or dry quarter
Other Gr. Neg. All 32 5% No None (mild/mod) or systemic (severe)

athe medical history of the cow must also be considered before making a decision to withhold antimicrobial therapy

Risks Associated With Mastitis Therapy
The use of antimicrobials to treat food animals has the potential to affect human health through 2 mechanisms: 1) increasing the risk of antimicrobial residues, and 2) influencing the generation or selection of antimicrobial resistant foodborne pathogens. In well regulated markets, the risk of antimicrobial residues in meat and milk is well known and is effectively controlled through intensive regulatory processes. However, there is increasing public concern about the impact of antimicrobial usage in food animals on the development of antimicrobial resistance. The use of antimicrobials for treatment of mastitis is naturally a focus of concern because most antimicrobial usage in adult dairy cows is for treatment or prevention of mastitis. While there is no compelling evidence that the use of IMM antimicrobials results in increased prevalence of resistant pathogens on U.S. dairy farms (Erskine et al., 2004, Pol and Ruegg, 2007) appropriate use of antimicrobials is a public health priority and ensuring judicious usage of antimicrobials in animal agriculture is a societal obligation that must be met.

Responsibilities Associated with Mastitis Treatment
Much antibiotic usage associated with treatment of clinical mastitis is difficult to justify because the infective bacteria is often gone before the inflammation is detected or the mastitis is caused by a type of bacteria that is not likely to respond to the types of drugs that are available. Mastitis is detected based on observation of inflammation, thus detection may occur after the successful clearance of pathogens by the immune system of the cow and these cases may be not benefit from IMM antimicrobial therapy (Smith et al., 1985). However, microbiologically negative cases may also occur when the animal remains infected but the quantity of colonies that is shed is less than the detection limit of the microbiological method used in the laboratory. In some of these instances, antimicrobial therapy may be beneficial. Likewise, it is difficult to justify the use of antimicrobial for most cases of non-severe mastitis caused by E coli. The majority of mild and moderate cases of mastitis caused by E. coli are spontaneously cured and it is difficult to justify the use of antimicrobials for these cases (Suojala et al., 2010, Suojala, et al., 2013).  Some researchers have reported no difference in bacteriological cure rates for untreated cows compared to cows treated for mastitis caused by Gram-negative pathogens, and the majority of antimicrobials labeled to treat mastitis have limited activity against these organisms (Pyorala, 1988, Pyorala et al., 1994, Suojala et al., 2013). A multi-herd clinical trial compared outcomes of a treatment protocol based on on-farm culture (cases caused by Gram-negative pathogens or no pathogen recovered were not treated) to outcomes of cows in a positive control group where all cases were treated with cephapirin (regardless of etiology) (Lago et al., 2011a,b). In some instances, greater bacteriological cure have been reported for clinical mastitis caused by a variety of Gram-negative pathogens treated using IMM ceftiofur (compared to non-treated control cows), however treatment did not significantly influence SCC or milk yield in the remainder of the lactation (Schukken et al., 2011). Knowledge of the type of bacteria that is causing the infection is important because the likely outcome of the infection and need for treatment are influenced by important characteristics that vary among pathogens. Increased use of rapid diagnostic methods (such as culture on-farm or in local veterinary clinics) to guide treatment decisions for non-severe cases of CM has the potential to improve judicious usage of IMM therapies and reduce antimicrobial usage on dairy farms.

Recommendations for Responsible Use of Antimicrobials For Treatment of Mastitis
1)    Milking technicians should be trained to detect cases early and aseptically collect milk samples. These samples should be used to rapidly arrive at a basic level of diagnosis (no growth, Gram positive or Gram negative) to guide therapy. Culturing using selective medias can occur either on-farm (large herds) or in local veterinary clinics (smaller herds). Cows affected with mild or moderate cases of clinical mastitis should be isolated and milk discarded for 24 hours until culture results are known. If the farmer wishes to immediately initiate treatment, the treatment can be stopped or the duration can be modified after culture results are known.

2)    Treatments should be administered only after a well-trained animal health manager has reviewed the medical history of the cow and evaluated prognostic factors for the case. Cows that are >3rd lactation, have a history of previous clinical cases, or have a history of chronically elevated SCC are often poor candidates for routine therapy. Treatment decisions for these cows should be based on culture results and review of treatment outcomes from similar cases on each farm. In many instances, “watchful waiting” (isolation of the cow and discard of the milk from the affected quarter) will be an appropriate therapy. In other instances, culling, cessation of lactation in an individual quarter or extended duration therapy may be preferred.

3)    Extended duration therapy is appropriate for some cases of mastitis but should be reserved for cases in which data indicates that it will improve case outcomes.

4)    Unless contraindicated by the medical history of the cow, no antimicrobial treatment should be administered to cows affected with pathogens for which no antimicrobials can be expected to be successful or for most cases that are culture negative at detection. Watchful waiting is the appropriate strategy for these cases.

5)    The use of antimicrobial treatment for mild cases of E coli mastitis should be considered when review of cow-level risk factors suggests that a chronic strain is involved. In the absence of other data, a thumb-rule is to initiate therapy if the cow has had increased SCC for >2 months or if the cow has risk factors that indicate her immune response may be compromised (first weeks of lactation, severe heat stress, very high production etc.).

6)    Outcomes of treatments should be routinely monitored. At a minimum the rate of recurrence (within 60-90 days) and SCC reduction (by 60 days) should be routinely evaluated.

Conclusion
Mastitis is detected based on observation of the cow immune response to infection. Many cases are bacteriologically negative when detected and will not benefit from antibiotic therapy. Other cases are caused by bacteria that cannot be expected to benefit from antibiotic therapy. Antibiotic treatments should be reserved for cases that will benefit. Veterinarians should be involved in developing and implementing mastitis treatment protocols and should work with farm personnel and other professionals to actively monitor outcomes of treatments that farm personnel administer. Research evidence is available to help guide mastitis treatment decisions and to better select animals that will benefit from specific treatments.

Ruegg, P.L., 2014.  Proc. Reg. Meeting National Mastitis Council, Aug 4-6, 2014, Ghent, Belgium, available in online:  www.nmconline.org

References

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Cow Talk with an Expert: Alternatives to Corn for Dairy Rations

By R. D. Shaver, Ph.D., PAS

Introduction

A two- to four-fold increase in corn prices in recent years over historical trends has prompted many questions about alternatives to corn for dairy rations. As corn is a low protein – high energy feedstuff, its continued use even with high prices or concern over its partial replacement is mainly confined to rations for lactating cows where meeting the energy requirements of milk production is important. Thus, rations for lactating cows will be the focus of this paper.

Since about three-fourths of the energy value of corn is provided by its starch content (calculated from NRC, 2001) and starch is thought to be an important carbohydrate fraction of lactating cow rations (Akins et al., 2012; Allen, 2012), the partial replacement of starch from corn grain with alternative starch or other carbohydrate sources will be discussed herein. Because corn price influences the price of corn alternatives, milk prices vary and partial corn replacement can impact lactation performance, it is imperative that the following parameters be closely evaluated when considering or implementing corn replacement strategies: feed cost per unit ration dry matter (DM), DM intake (DMI), total feed cost per cow, milk yield, composition and component yields, actual and component-corrected feed efficiencies, income over feed costs (IOFC), and body condition.

Corn Alternatives

Byproduct Corn Starch

Krause et al. (2003) fed total mixed rations (TMR) containing 0, 6, 12 or 18% refined corn starch (RCS; DM basis) to mid-lactation Holstein cows. Dry cracked shelled corn was reduced from 39% to 14% and dry corn gluten feed (DCGF) increased from 0% to 6% of ration DM for 0% compared to 18% RCS rations. Dietary starch content averaged 31% (DM basis) across the four treatments. Milk yield was unaffected by treatment, but DMI, energy-corrected milk yield (ECM), and milk fat and protein percentages were greatest for the 6% RCS treatment. Greatest ECM/DMI was observed for the 18% RCS treatment, and coincident with the greatest ruminal propionate concentration which can influence DMI (Allen et al., 2009; Oba and Allen, 2003). Possibly the reduction in milk fat by 0.29%-units on average observed for the 12% and 18% RCS treatments could have been avoided at reduced dietary starch concentrations.

Barley and Wheat Grain

A recent meta-analysis addressed the performance of lactating dairy cows fed barley or wheat compared to corn (Ferraretto et al., 2013). Cows fed corn-grain based diets consumed 5.7 lb/d more DM, on average, than cows fed barley- or wheat-grain-based diets. Milk and fat-corrected milk (FCM) yields were 7.9 and 9.0 lb/day per cow, respectively, greater, on average, for corn- than barley- or wheat-grain based diets. Actual milk and FCM feed efficiencies were unaffected by treatment. Likewise, milk fat, protein, and urea nitrogen concentrations were unaffected by treatment and averaged 3.51%, 3.13%, and 13.7 mg/dL, respectively.

Ruminal starch digestibility was 17%-units and 25%-units greater for barley and wheat, respectively, than corn. Total tract starch digestibility did not differ among treatments. Ruminal and total tract NDF digestibility (NDFD) were similar among treatments. Greater rate and extent of ruminal starch digestion and greater ruminal protein degradability need to be accounted for when formulating rations with barley or wheat as opposed to corn. This is often accomplished by partial rather than full replacement of corn with these alternative cereal grains.

Hominy Feed

Cooke et al. (2009) compared hominy feed (HF) to DGSC and steam-flaked corn (SFC) in mid lactation dairy cows fed varying proportions of corn silage and ryegrass silage. Starch and NDF concentrations of the HF were 47% and 26% (DM basis), respectively, compared to 66% and 14%, on average, for DGSC and SFC. By comparison the NRC (2001) shows NDF content for HF of 21.1% ± 5.5 (DM basis), which would put starch content at about 52% on average by difference calculation. The HF, DGSC and SFC were each fed at 35%, 33%, 30% and 28% of ration DM as the proportion of corn silage in the forage mixture increased from 0 to 25%, 50% and 75%. Dietary starch concentrations were 2%- to 4%-units lower for HF- compared to DGSC- and SFC-based TMR.

The DMI was greater and milk fat content tended to be greater for DGSC than HF or SFC, while milk yield was similar averaging 31 kg/d per cow across the treatments. Total tract DM and organic matter digestibilities were greater for HF and SFC than DGSC, but NDFD was reduced for HF compared to DGSC and SFC. While starch digestibility was not reported, the above results in concert suggest greater ruminal and total tract starch digestibilities for HF than DGSC which would not be unexpected considering the fine particle size of HF (Larson et al., 1993).

Sugar Supplements

Broderick and Radloff (2004) partially replaced starch from high-moisture shelled corn with sugar from either dried (Trial 1) or liquid (Trial 2) molasses. Dietary starch and total sugar concentrations (DM basis) ranged from 31.5% to 23.2% and 2.6% to 7.2%, respectively, in Trial 1, and from 31.4% to 26.1% and 2.6% to 10.0% in Trial 2. The estimated overall optimum for total dietary sugar, based on yields of fat and FCM in Trial 1 and yields of milk and protein in Trial 2, was 5.0% (DM basis); feeding diets with more than 6% total sugar with the added sugar from molasses appeared to depress milk production. Broderick et al. (2008) partially replaced byproduct corn starch with sucrose. Dietary starch and total sugar concentrations (DM basis) ranged from 28.2% to 21.5% and 2.7% to 10.0%, respectively. Milk yield was unaffected by treatment, but milk fat yield was greatest for the diet containing 7.1% total sugar and 24.5% starch (DM basis).

Alternatives for high-sugar ingredients include molasses, whey, whey permeate, liquid feed supplements, and sucrose. For an excellent review on the feeding of whey permeate, readers are referred to Cotanch et al. (2006). Wet sugar additives, such as liquid feed supplements, liquid molasses, whey or whey permeate, may also improve palatability and (or) reduce sorting of the TMR.

Glycerin

Donkin et al. (2009) evaluated glycerin, a byproduct of biodiesel production, as a replacer of corn in rations fed to lactating dairy cows. Refined glycerin (RG) was included in TMR at 0, 5, 10 and 15% of ration DM while DGSC was reduced from 20% to 3% of ration DM for zero to the highest level of RG addition. Lactation performance was unaffected by treatment in late lactation cows averaging about 37 kg/d per cow.

Shin et al. (2012) evaluated crude glycerin (CG; 0.4% methanol) as a replacer of concentrate ingredients including DGSC in rations fed to mid lactation dairy cows fed two different roughage sources. The CG was included in TMR at 0, 5, and 10% of ration DM while DGSC was reduced from 18% to 8% (corn silage as main roughage source in low total NDF rations) or 32% to 22% (cottonseed hulls as main roughage source in low forage NDF rations) for zero to the highest level of CG addition. Milk fat content and yield and total tract NDFD were reduced by feeding the 10% CG ration for both roughage sources, while feeding the 5% CG ration increased DMI but not milk yield. Feeding CG increased FCM/DMI for the corn silage based rations but decreased FCM/DMI for the cottonseed hulls based rations. Molar proportions of ruminal propionate, butyrate and valerate were increased while acetate was decreased by feeding CG.

High Fiber – Low Starch Byproduct Feeds

There are a myriad of high NDF – Low Starch byproducts (HFLS) fed to dairy cows (Shaver, 2005). The HFLS can be used to partially replace corn grain, forage or both depending on ration nutrient needs and ingredient availability and price. Low protein HFLS, such as soy hulls (SH) or beet pulp which are high in digestible or soluble fiber, usually get used for a direct pound for pound corn replacement. Whereas, middle protein HFLS, such as CGF, brewers grains or distillers grains, often partially replace both corn grain and oilseed meals on a protein equivalence basis; i.e. one lb. DM of HFLS replaces about 0.5 lb. corn and 0.5 lb. oilseed meal. Alternatively, these middle protein HFLS can be used to partially replace forage NDF (Bradford and Mullins, 2012). Whole cottonseed (WCS) and cottonseed hulls are the classic middle and low protein, respectively, HFLS forage replacers.

We conducted four recent continuous-lactation (12 – 14 weeks on treatment) feeding experiments at UW-Madison (Gencoglu et al., 2010; Ferraretto et al., 2011 and 2012; Akins et al., 2012) to evaluate HFLS as partial corn grain replacers in mid lactation cows. The forage-NDF concentrations were 20% – 21% across all diets with 5% to 10%-units less starch for reduced-starch (RS) than normal-starch (NS) diets. Milk yield for cows fed the NS diet ranged from 42 to 52 kg/cow/d across the four trials.

Dry matter intake was greater for RS than NS in 3 of 4 trials (unaffected by treatment in Akins et al., 2012). Greater DMI for RS than NS may be related to reduced ruminal propionate concentration (Allen, 1997; Beckman and Weiss, 2005) leading to increased meal size and consequently greater DMI (Allen et al., 2009).

Actual milk yield was similar for cows fed RS and NS in two trials with SH (Gencoglu et al., 2010; Ferraretto et al., 2012), was lower for RS than NS in the SH trial of Akins et al. (2012), and tended to be lower for RS than NS in the trial with WCS and wheat midds (WM; Ferraretto et al., 2011). Because WCS and WM are moderate-protein HFLS, they partially replaced both corn grain and soybean meal (SBM) in the RS diet (Ferraretto et al., 2011). Greater ruminal protein degradation for these ingredients compared to SBM along with reduced rumen microbial protein production for RS may have decreased metabolizable protein flow, which could partially explain the decrease in milk yield (NRC, 2001).

Responses for milk yield corrected for concentrations of fat, protein and lactose (solids-corrected milk;SCM) were inconsistent with either greater (Gencoglu et al., 2010), trend for lower (Ferraretto et al., 2011), or similar (Ferraretto et al., 2012; Akins et al., 2012) SCM observed for RS compared to NS. A recent meta-analysis by Ferraretto et al. (2013) found that milk yield and protein content were increased and fat and urea nitrogen contents decreased with increasing dietary starch concentrations. Body weight gain was not different for cows fed RS compared to cows fed NS across the four UW Madison trials. Ruminal and total tract NDF digestibilities decreased with increasing dietary starch concentrations in the meta-analysis reported by Ferraretto et al. (2013).

Feed efficiencies, across the four trials, were reduced for RS compared to NS by 2% to 12% for Milk/DMI and by 1% to 11% for SCM/DMI. Reduced feed efficiency for dairy cows fed RS diets creates an economic concern for nutritionists desiring to use this formulation strategy to reduce diet cost per unit of DM. Midwest USA market prices for feed ingredients and milk were applied to ration ingredient composition, DMI and milk production data from the four trials to estimate feed costs and IOFC. Feed costs per unit DM were reduced in all four trials by 1% to 8% for RS. Feed costs per cow per day for RS, however, were increased for two trials by 3% to 8% and decreased for two trials by only 1% to 2%. Estimates of IOFC were unaffected in one trial, and decreased in three trials by 4% to 7% for RS.

Feed efficiency and IOFC results indicate that for high producing cows in early- to mid- lactation, partially replacing corn grain with HFLS to formulate RS diets was not beneficial. Reduced market prices for HFLS relative to corn grain and soybean meal would improve the economics of feeding RS compared to NS diets. Furthermore, RS diets formulated by partially replacing starch from corn grain with NDF from HFLS may offer more potential for beneficial responses when fed to lower producing, later lactation cows than evaluated in the trials reviewed herein (Allen, 2012; Bradford and Mullins, 2012). Also, the use of HFLS to partially replace forage NDF may allow for the feeding of RS diets without sacrificing lactation performance (Bradford and Mullins, 2012).

Monensin. Akins et al. (2012) hypothesized that monsensin would reduce DMI and thus improve efficiency (Duffield et al., 2008) more with RS than NS rations. The RS ration was formulated by partially replacing DGSC with SH. Mid-lactation dairy cows (n = 128) were stratified by breed, parity and days in milk, and randomly assigned to one of 16 pens with 8 cows each per pen in the UW-Madison Emmons-Blaine Arlington free-stall, parlor facility. Pens were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of treatments (RS vs. NS and Control vs. Monensin) for a continuous-lactation feeding trial. Inclusion of monensin in the TMR at 18 g/ton DM improved lactation performance and measures of feed efficiency for both RS and NS rations. There were few significant interactions between dietary starch content and monensin supplementation, thereby supporting the use of monensin in both normal- and reduced-starch rations. Dietary monensin supplementation increased ration net energy content by 2.8% as calculated from body weight, weight gain, milk energy output and DMI data. Based on trial DMI and an assumed net energy content of DGSC (NRC, 2001), this increase in energy utilization calculated to a corn grain equivalency for monensin of 1.5 lb/day per cow (as fed basis).

Fat Supplements

The energy density of fat supplements can be 2.5 to 3 times the energy density of DGSC depending on the fat source (NRC, 2001). With today’s increased corn prices the economics of supplemental fat feeding along ration fat limits should be re-evaluated. Ruminal inertness and fatty acid composition of fat supplements is highly important to minimize milk fat depression (He et al., 2012).

Conclusions

There are numerous nutritional alternatives to corn available for inclusion in dairy cattle rations. The challenge, however, is to determine whether or not they are economical alternatives, which is important since their prices are often closely related to corn price and there can be some lactation performance risks associated with their use. FeedVal 2012 (Cabrera et al., 2012) and Sesame (St-Pierre and Cobanov, 2011) are useful decision tools for assessing the dollar value of feed ingredients on a nutrient basis relative to other available feed ingredients upon which to base feed purchase decisions. Least cost ration formulation to pre-set nutrient specifications with feed ingredients available in inventory and monitoring of lactation performance are highly important for successful implementation of corn replacement strategies.

References

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Akins, M.S., K.L. Perfield, H.B. Green, R.D. Shaver. 2012. Effects of Rumensin in lactating cow diets with differing starch levels. Proc. High Plains Dairy Conf. Amarillo, TX.

Allen, M.S. 2012. Adjusting concentration and ruminal digestibility of starch through lactation. Pages 24-30 in Proc. Four-State Dairy Nutr. & Mgmt Conf. Dubuque, IA.

Allen, M.S. 1997. Relationship between fermentation acid production in the rumen and the requirement for physically effective fiber. J. Dairy Sci. 80:1447-1462.

Allen, M.S., B.J. Bradford, and M. Oba. 2009. The hepatic oxidation theory of the control of feed intake and its application to ruminants. J. Anim. Sci. 87:3317-3334.

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He, M., K.L. Perfield, H.B. Green, and L.E. Armentano. 2012. Effect of dietary fat blend enriched in oleic or linoleic acid and monensin supplementation on dairy cattle performance, milk fatty acid profiles, and milk fat depression. J. Dairy Sci. 95: 1447-1461.

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Both students and dairies win with new Badger Dairy Challenge

Written by Adam Hinterthuer, freelance writer for CALS

Four women dressed in business attire stood at the head of a conference table, backlit by the glow of charts projected on a screen behind them. Fiddling with their notes, they waited for the verdict of the industry professionals that had just heard their presentation.

A week earlier, Cara Biely, Carrie Warmka, Cassie Endres and Laura Finley, all undergraduates in the UW-Madison Department of Dairy Science, had toured Statz Brothers Farms in Sun Prairie. For two hours, they’d observed the dairy in action, taking notes on everything from the milking schedules of the farm’s 3,000 cows, to several months of financial statements. During the tour, they’d identified a problem: The farm was overcrowded. The Statz Brothers’ cows were in excellent health, but the dairy was missing out on optimal milk production while it waited for new facilities to be completed to ease the crowding problem.

“Overcrowding has an affect on milk production,” Cara Biely had noted in her report to the judges. “Transition cows could go through the parlor three times a day with all of the other ones making it through twice.” If the dairy could find a way to up production by even a couple of pounds per cow, she said, “The money is going to add up quickly.”

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Now, Biely waited with the rest of her team to hear what the judges, consisting of a dairy farmer, veterinarian, nutritionist, and financial specialist thought of their recommendations.

It was part of the first-annual Badger Dairy Challenge, and it turned out to be an invaluable event not just for the students but, potentially, for Statz Brothers Farms.

A little over a decade ago, the North American Intercollegiate Dairy Challenge appeared on the dairy competition scene.  Where traditional dairy judging recognized talent in appraising and evaluating individual cows, Dairy Challenge was created to focus on the science and business of managing entire herds.  Teams tour a farm and then prepare a report assessing management categories such as reproduction, nutrition, milking, and farm financials.

The events have become extremely popular, says dairy management instructor, Ted Halbach.

“There are now thirty-two schools that compete at the national level of Dairy Challenge,” Halbach says. “It’s overtaken dairy cattle judging as far as the number of universities that compete in their national contest.” While UW students have done really well in them, he says, those participants have all come out of Dairy Science 535, a course that seniors don’t take until spring semester.

In an attempt to introduce students to the competition well before the final semester of their undergraduate careers, Halbach organized the Badger Dairy Challenge. “We’re trying to build a culture of enthusiasm for the event among our undergraduates,” he says.  “I think a lack of familiarity with the contest has made some students timid when it comes to competing at the regional and national levels.  We want them to gain confidence in their abilities by first experiencing the event format with their peers.”

If the inaugural Badger Dairy Challenge was any indication, Halbach is succeeding in this goal. While 12 upperclassmen divided into three teams for the “Legends” division, twice as many freshmen participated in the “Leaders” bracket. Megan Opperman, one of those freshmen, says the decision was easy.

“We heard about it in our animal sciences class and I thought it would be really fun to do with my friends,” she says. “I also thought it was a really good opportunity and something that employers are going to be looking for [on my resume].”

Opperman, a first-year student from Rockford, Illinois, hopes to work in the dairy industry in either genetics or nutrition. Her participation in dairy challenges will, indeed, help her get there, says Molly Sloan, global skills development specialist for Alta Genetics. Seven years ago, Sloan was a UW-Madison student competing in regional and national dairy challenges. Today, she attends the events in search of potential employees. “When I look to hire interns or full time employees, one of the first things I look for on a resume is Dairy Challenge experience and exposure. [It’s] the single-best event available to students to prepare them for realistic situations they will face in the dairy business,” she says.

Sloan served as a judge at the Badger Dairy Challenge and says she was impressed by how students took what they’d seen on their farm visits and used it to identify limitations for profitability and production.

Limitations are is exactly what Cara, Carrie, Cassie and Laura had done in their assessment of Statz Brothers Farms.

Adam Ward, who is a veterinarian in the practice that services the Statz herd, was a judge in the room during their presentation. He says the women identified an issue the dairy was already wrestling with, but he never expected to uncover a potential solution during what was supposed to be a training exercise for undergrads.

Yet, as the judges deliberated, an idea emerged to tweak the milking schedule and see if they could push peak milk up in one group of cows. Ward took the idea back to the farm and says, “They were keen to try it, so we decided to implement it. We won’t know if it did anything for a few months, but it’s kind of cool that this educational event led to a real-world change.” It’s especially when the change could potentially net Statz Brothers Farms thousands more in annual profits.

For Ward, it confirms how useful dairy challenges are in training students for a future in the industry. Where cow judging rewards a singular and specialized level of knowledge that’s often cultivated from a young age, dairy challenges open the doors for broader participation in all levels of management.

“Maybe someone knows nothing about cows,” he says, “but they are a finance person or business person and can provide some input into the financials of a farm. They may not know a bunker from a silo, but they’re still a valuable member of your team.”

The report from Cara Biely’s team netted `a second-place finish. But, more important than the ranking, it solidified their interest in their chosen field. If the dairy challenge is any indication of what a career in the industry is like, Biely says, sign her up. “If you like it, you like it,” she says. “It kind of gets in your blood and that’s the only thing you want to do.”

A high-resolution version of the above photo is available at: http://flic.kr/p/irTiT2