Decreased concentration of serum apolipoprotein C-III in cows with fatty liver, ketosis, left displacement of the abomasum, milk fever and retained placenta

Apolipoprotein (apo) C-III is a low molecular mass protein mainly distributed in the high-density lipoprotein (HDL) fraction. In cows with postparturient diseases such as ketosis, concentrations of cholesterol, phospholipids and apoA-I and the activity of lecithin:cholesterol acyltransferase, which are mainly distributed in or functionally associated with HDL, are reduced. The purpose of the present study was to examine whether the serum concentration of apoC-III was similarly decreased in the postparturient diseases. Compared with healthy controls, the apoC-III concentration was significantly (P<0.01) decreased in cows with fatty liver, ketosis, left displacement of the abomasum, milk fever and retained placenta. Concentrations of apoC-III in the HDL fractions from diseased cows were also lower than in controls. Of the diseased cows, the decreased apoC-III concentration was particularly distinct in cows with milk fever. Increased nonesterified fatty acid and reduced free cholesterol, cholesteryl ester and phospholipid concentrations were observed in cows with milk fever, as in the other diseased cows. The decrease in the apoC-III concentration is suggested to be closely associated with the postparturient disorders, in particular with milk fever.

Field study of dairy cows with reduced appetite in early lactation: clinical examinations, blood and rumen fluid analyses

The study included 125 cows with reduced appetite and with clinical signs interpreted by the owner as indicating bovine ketosis 6 to 75 days postpartum. Almost all of the cows were given concentrates 2 to 3 times daily. With a practitioners view to treatment and prophylaxis the cows were divided into 5 diagnostic groups on the basis of thorough clinical examination, milk ketotest, decreased protozoal activity and concentrations, increased methylene blue reduction time, and increased liver parameters: ketosis (n = 32), indigestion (n = 26), combined ketosis and indigestion (n = 29), liver disease combined with ketosis, indigestion, or both (n = 15), and no specific diagnosis (n = 17). Three cows with traumatic reticuloperitonitis and 3 with abomasal displacement were not grouped. Nonparametric methods were used when groups were compared. Aspartate aminotransferase, glutamate dehydrogenase, gamma-glutamyl transferase and total bilirubin were elevated in the group with liver disease. Free fatty acids were significantly elevated in cows with ketosis, compared with cows with indigestion. Activity and concentrations of large and small protozoas were reduced, and methylene blue reduction time was increased in cows with indigestion. The rumen fluid pH was the same for groups of cows with and without indigestion. Prolonged reduced appetite before examination could have led to misclassification. Without careful interpretation of the milk ketotest, many cases with additional diagnoses would have been reported as primary ketosis. Thorough clinical examination together with feasible rumen fluid examination and economically reasonable blood biochemistry did not uncover the reason(s) for reduced appetite in 14% of the cows. More powerful diagnostic methods are needed.

Postexercise ketosis in night-migrating passerine birds

This study investigated the postexercise metabolism of six species of free-living, night-migrating passerine birds (European robin, pied flycatcher, wheatear, redstart, blackcap, and garden warbler). The birds were caught during autumn migration out of their nocturnal flight, and their metabolism changed from a fasting, highly active state to a fasting, resting state. Concentrations of six plasma metabolites of the fat, carbohydrate, and protein metabolism were measured during up to 10 h of recovery time. The metabolic changes indicated a biphasic pattern: (a) a quick first response to the reduced energy demands during the first 20 min of recovery, suggested by an increase and subsequent decrease of free fatty acid levels, and (b) subsequently, a postexercise ketosis and a reduction of lipolysis and proteolysis, suggested by high beta-hydroxy-butyrate and low free fatty acid, glycerol, triglyceride, and uric acid levels. This metabolic pattern differs from that of humans and rats, in which ketosis starts immediately postexercise or is absent in trained subjects. Since migrating birds are naturally adapted to endurance exercise, it is hypothesized that the high and long-lasting postexercise ketosis does not evoke physiological problems (such as hypoglycemia) but, by contrast, increases the ability of birds to rely on lipids, to a very high extent, during and after flight and decreases the dependence on glucose and glucogenic amino acids. Differences between species in fat stores and metabolic pattern support this hypothesis.

Reduction in serum lecithin:cholesterol acyltransferase activity prior to the occurrence of ketosis and milk fever in cows

Lecithin:cholesterol acyltransferase (LCAT) is the enzyme responsible for production of cholesteryl esters in plasma. The LCAT activity is reduced in cows with fatty liver developed during the nonlactating stage and those with the fatty liver-related postparturient diseases such as ketosis. The purpose of the present study was to examine whether reduced LCAT activity during the nonlactating stage could be detected before the occurrence of postparturient diseases. Sera from 24 cows were collected at approximately 10-day intervals from -48 to +14 days from parturition. Of the 24 cows, 14 were apparently healthy, whereas 7 had ketosis and 3 had milk fever at around parturition. Of the 14 healthy cows, 7 had unaltered LCAT activity during the observation period, whereas 7 showed reduced activity from -20 to +14 days. Ketosis and milk fever occurred at from -3 to +10 days, but reductions of LCAT activity in diseased cows had already been observed from days -20 to 0. These results suggest that LCAT activity is virtually unaffected during the peripartum period at least in some healthy cows and also that the reduction in LCAT activity can be detected before the occurrence of ketosis and milk fever.

Dry cow management for the prevention of ketosis and fatty liver in dairy cows

Dramatic increases in energy requirements during late gestation and early lactation, superimposed on an animal with a profound drop in DMI just before calving, make the dairy cow highly susceptible to the metabolic diseases ketosis and hepatic lipidosis. Increased serum concentrations of NEFA appear to be causally linked to these problems, and feeding strategies to reduce or avoid this dramatic increase are desirable for optimal health and performance. During the last 3 to 4 weeks prepartum, a diet higher in energy and protein concentration than current NRC recommendations should be fed so that adequate nutrient intake occurs within the limits of the reduced DMI. The additional energy should be provided by glucose precursors, such as starchy concentrates or propylene glycol, and not by lipid. Excessive energy and reduced fiber should be avoided both early in the dry period (more than 28 days prepartum) and immediately postpartum. Attention should be paid to the environment of the cow, especially during the last 3 weeks prepartum, to avoid environmental stressors as much as possible.

Ruminant adaptation to negative energy balance. Influences on the etiology of ketosis and fatty liver

Ketosis and fatty liver occur when physiologic mechanisms for the adaptation to negative energy balance fail. Failure of hepatic gluconeogenesis to supply adequate glucose for lactation and body needs may be one cause of ketosis; however, poor feedback control of nonesterified fatty acid release from adipose tissue is another likely cause of ketosis and fatty liver. The types of ketosis resulting from these two metabolic lesions may require different therapeutic and prophylactic approaches.

Subclinical ketosis in lactating dairy cattle

Subclinical ketosis is an important and common condition of early-lactation dairy cattle. It is associated with losses in milk production and increased risk of periparturient disease. Prevention depends on several factors, including proper transition-cow nutrition, management of body condition, and the use of certain feed additives such as niacin, propylene glycol, and ionophores. All currently available cowside tests for subclinical ketosis have certain limitations in their use. Effective monitoring schemes for subclinical ketosis can be developed, however, and these may be useful in many herd health programs.

Metabolic aspects in the etiology of displaced abomasum

Results of studies on metabolic variables that exist prior to the diagnosis of displaced abomasum (DA) indicate that subclinical ketosis is a risk factor for DA. Serum aspartate aminotransferase activity, serum and milk betahydroxybutyric acid concentrations, and milk fat-to-protein ratios were often elevated before the diagnosis of DA, and these variables may be used to predict DA. Prevention of subclinical ketosis may prevent DA.

Glucagon as a potential therapy for ketosis and fatty liver

An experiment demonstrating the usefulness of glucagon as a treatment for fatty liver and ketosis in early-lactation dairy cows has been described. This is the first report of the ability of glucagon, or any agent, to promote clearance of lipid from livers of animals suffering hepatic lipidosis. The development and use of glucagon as a therapeutic agent for the fatty-liver complex in dairy cows may provide a powerful management tool to enhance the profitability of the high-producing dairy cow.

Effect of disease on reproduction in the dairy cow: a meta-analysis

Effects on reproduction of dystocia, stillbirth, abortion, milk fever, retained placenta, metritis, cystic ovaries, anestrus, ketosis, displaced abomasum, locomotor disorders, and mastitis were reviewed. Papers were considered if they provided quantitative estimates of diseases on days to first estrus, days to first service, conception rate at first service, days from first service to conception, days to conception or days open, calving interval, conception rates at various days post partum (dpp), and number of services per conception or per cow. Only papers in English in peer-reviewed journals were selected for analysis of post 1960 data from intensive dairy regions. Seventy papers fulfilled the selection criteria. Summary estimates of disease effects were calculated according to meta-analysis methods, and study designs were described in detail to identify possible heterogeneity of the results. Stillbirth, milk fever, displaced abomasum and mastitis had no effect on reproduction. Clinical ketosis, dystocia and retained placenta were associated with 2 to 3 more days to first service and with a 4 to 10% lower conception rate at first service, resulting in 6 to 12 more days to conception. Locomotor disorders were associated with an average increase of 12 d to conception, with wide variation depending on lesions and stage of occurrence. Metritis was associated with 7 more days to first service, 20% lower conception rate at first service, resulting in 19 more days to conception. Cystic ovaries were associated with 6 to 11 more days to first service and with 20 to 30 more days to conception. Anestrus was associated with 26 more days to first service and with an 18% lower conception rate at first service, resulting in 41 more days to conception. Abortion was associated with 70 to 80 more days to conception.

Evaluation of eight cow-side ketone tests in milk for detection of subclinical ketosis in dairy cows

The objective of this study was to evaluate eight cowside ketone tests when used with milk for detection of subclinical ketosis. A total of 469 dairy cows in the first week of lactation were studied. Twelve percent of these cows had subclinical ketosis, defined as >1400 micromol of beta-hydroxybutyrate/L of blood serum. The Pink test liquid and the Ketolac test strip were highly sensitive for subclinical ketosis when used with milk. The Uriscan and Rapignost test strips were poorly sensitive; the Ketostix, Ketur-Test, and Medi-Test-Keton test strips and the Acetonreagenz test tablet were insensitive for subclinical ketosis when used with milk. Pink and Ketolac milk ketone tests are potentially useful tools for use in a routine monitoring program to detect subclinical ketosis in early postpartal dairy cows.

Effect of a monensin-controlled release capsule on cow health and reproductive performance

Dry cows and pregnant heifers from 25 farms near Guelph, Ontario, Canada were enrolled in a large, double-blind, randomized clinical trial designed to evaluate the impact of monensin on energy metabolism, health, and production. A total of 503 cows was given monensin in controlled-release capsules, and 507 cows were administered placebo capsules 3 wk before expected calving date. The effects of treatment on health were evaluated using a logistic regression model. Treatment with monensin significantly reduced the incidence of abomasal displacement (OR = 0.41-0.84) and multiple illnesses (OR = 0.38-0.89). Monensin treatment tended to reduce the incidence of clinical ketosis (P = 0.11) and the risk of being culled (P = 0.09) in the first 94 d of lactation. Reproductive performance was analyzed with both a logistic regression model for conception rate and a survival analysis for days to first breeding and days from calving to conception. Treatment with monensin had no significant effect on any measure of reproductive performance.

Screening of dairy cows for ketosis by use of infrared spectroscopy and multivariate calibration

A fast and inexpensive method of screening ketosis in cows is presented. This method is based on the determination of acetone in bovine milk by using Fourier transform infrared spectroscopy combined with multivariate calibration. Only samples with a naturally increased acetone content could be used in the calibration step; samples containing added acetone did not produce an acceptable calibration equation. On test samples ranging from 0.0 to 2.8 mM acetone, an R2 of 0.81 and an accuracy (root mean square error of prediction) of 0.27 mM were obtained. This accuracy was sufficient to classify the cows into two groups: healthy and possibly ketotic. No false negatives were determined for the present data set.

Alleviation of fatty liver in dairy cows with 14-day intravenous infusions of glucagon

Twenty multiparous cows were fed additional concentrate during the final 30 d prepartum to cause susceptibility to fatty liver. From 14 to 42 d postpartum, all cows were subjected to a protocol to induce fatty liver and ketosis. To test glucagon as a treatment for fatty liver, either glucagon at 10 mg/d or excipient was infused via the jugular vein from 21 to 35 d postpartum. All cows had fatty liver at 14 d postpartum and became ketonemic and hypoglycemic during the induction of ketosis. Glucagon increased plasma glucose to 142% of that of controls throughout the 14-d treatment. The hypoinsulinemia present in cows with fatty liver was not affected by glucagon. Plasma beta-hydroxybutyrate and nonesterified fatty acids were decreased by glucagon. At 6 d postpartum, liver triacylglycerol averaged 12.9% of liver (wet weight basis). Glucagon had decreased triacylglycerol content of livers by 71% at d 35. Glycogen was 1.0% of the wet weight of livers at 6 d in milk, but it was decreased by glucagon to 0.5% at 2 d after glucagon began. Glycogen then increased in cows treated with glucagon until at 38 d in milk liver glycogen was 3.7% versus 1.6% in controls. Our results document that glucagon decreases the degree of fatty liver in early lactation dairy cows, which also decreases the incidence of ketosis after alleviation of fatty liver.

Regulation of messenger ribonucleic acid expression for gluconeogenic enzymes during glucagon infusions into lactating cows

The effects of glucagon infusions on expression of mRNA for enzymes that regulate gluconeogenesis were studied in lactating cows. Normal cows and cows with fatty liver that were susceptible to ketosis were assigned to either glucagon-treated or control groups. Glucagon at 0 or 10 mg/d was infused for 14 d beginning at d 21 postpartum. In normal cows, glucagon infusions increased concentrations of both plasma glucagon and glucose, which caused plasma insulin to increase. Consequently, hepatic phosphoenolpyruvate carboxykinase mRNA decreased during wk 1 of glucagon infusions. Glucagon infusions into cows with fatty liver also increased plasma glucagon and glucose, but concentrations of plasma insulin and hepatic phosphoenolpyruvate carboxykinase mRNA did not change. More phosphoenolpyruvate carboxykinase mRNA was present in the livers of cows with fatty liver than in livers of normal cows. In a follow-up experiment with midlactation cows, 3.5-h infusions of glucagon at 14 mg/d increased plasma glucose and insulin and decreased plasma nonesterified fatty acids and hepatic glycogen. Hepatic phosphoenolpyruvate carboxykinase mRNA was decreased 41%, pyruvate carboxylase mRNA was increased 50%, but fructose-1,6-bisphosphatase mRNA did not change. We conclude that the expression of the hepatic phosphoenolpyruvate carboxykinase gene in normal cows is inhibited by insulin to balance elevated carbohydrate status during glucagon infusions; however, inhibited expression of hepatic phosphoenolpyruvate carboxykinase mRNA probably is not involved in the pathogenesis of lactation ketosis.

Effects of diseases on test day milk yield and body weight of dairy cows from Danish research herds

The pre- and postdisease interrelationships of energy corrected test day milk yield and body weight of dairy cows caused by mastitis, three reproductive disorders (retained placenta, metritis, cystic ovaries), and seven metabolic disorders (milk fever, ketosis, decreased rumen motility, enteritis, left displaced abomasum, right displaced abomasum, and off feed) were quantified by using mixed models analysis with repeated measures of continuous data. The data were weekly recordings from 4414 lactations collected in three Danish research herds. High milk yield was a risk factor for ketosis and enteritis. Heavier primiparous cows were more likely to contract mastitis. Milk yield was decreased for a disease-specific period for all study diseases except cystic ovaries and right displaced abomasum. Metabolic disorders had a detrimental effect on body weight. The highest weight loss (69 kg) was associated with left displaced abomasum. The persistence of the weight loss differed considerably among study diseases. Almost all weight loss occurred up to and including the initial week after diagnosis, which emphasized the detrimental effect of the subclinical stage. However, weekly measured body weight seemed superior to weekly energy corrected test day milk yield for disease detection only for decreased rumen motility and left displaced abomasum. This study demonstrates the importance of the predisease level for accurate estimation of the loss of milk yield and body weight from disease.

Prevalence of ketonemia and associations with herd size, lactation stage, parity, and postparturient diseases in Jordanian dairy cattle

The prevalence of bovine ketonemia among 1155 dairy cows in various stages of lactation and parity on 25 Jordanian dairy herds was studied. The cross-sectional study was conducted during the spring of 1992. Serum concentration of beta-hydroxybutyrate (BHB) <0.9 mmol/l, between 0.9 and 1.7 mmol/l, and >1.7 mmol/l were considered to indicate normal, mild and severe ketonemia, respectively. The point prevalences of mild and severe ketonemia were 22% and 3.8%, respectively. The prevalence of ketonemia decreased with increasing herd size. Associations between the prevalence of ketonemia and parity, stage of lactation, metritis, somatic-cell count (SCC) and serum cholesterol levels were not significant (p > 0.05).

Beta-hydroxybutyrate levels in peripheral blood and ketone bodies supplemented in culture media affect the in vitro chemotaxis of bovine leukocytes

The role of ketone bodies on chemotactic capacities of leukocytes was characterized in two experiments. Experiment I was performed to investigate the association between serum beta-hydroxybutyrate concentrations (BHB) and in vitro chemotaxis of leukocytes. Cows were divided into low-BHB, medium-BHB, and high-BHB ones and classified according to their BHB. Leukocytes from high-BHB cows had a significantly lower chemotactic differential than leukocytes from low-BHB cows (p < 0.01). The effect of adding ketone bodies into in vitro chemotaxis cultures on leukocytes chemotaxis was studied in Experiment II. Either individual or a combination of commercial ketone bodies - sodium salts of BHB (BHBA), lithium salt of acetoacetate (ACAC), and acetone (Acetone) - were diluted in culture media and divided into eight concentrations corresponding to concentrations of bovine subclinical and clinical ketosis. For leukocytes from medium- and high-BHB cow, the chemotactic indexes of leukocytes were reduced by ACAC and Acetone. Chemotactic differentials of cultures with ACAC and acetone supplementation from both sources of leukocytes were significantly lower than that of the control culture (p < 0.05). For leukocytes from high-BHB cows, chemotactic indexes were suppressed in a ketone-body environment. In conclusion, leukocytes from naturally-occurring ketotic cows have lower chemotactic differentials than those from non-ketotic cows, and a chemotactic capacity indicated by a chemotactic differential is impaired when leukocytes migrate in an environment with ketone bodies in vitro.

Analysis of correlated continuous repeated observations: modelling the effect of ketosis on milk yield in dairy cows

This study used mixed models analysis to demonstrate the advantages of a repeated measures technique for a continuous variable over a single measure technique. As an illustration, the loss of milk yield due to ketosis was studied in 2604 multiparous New York State Holstein cows belonging to eight herds, calving between 1991 and 1993. Two methods of analysis were presented: The first treated milk yield as a continuous, summary measure (projected 305-day milk yield); the second treated milk yield as repeated measurements (test-day milk yields). In the first example, with 305-day milk yield as the outcome, ketosis was treated as a binary covariate. Ketosis had no effect on the 305-day milk yield. In the second example, with monthly test-day milk yields as the outcome, four different covariance structures (simple, compound symmetry, autoregressive, and unstructured) to model the association among the repeated measurements were compared. With this approach, ketotic cows yielded significantly less milk per day both before and immediately after diagnosis than did non-ketotic cows. Based on the goodness-of-fit statistics, it was unclear whether an autoregressive or unstructured covariance structure was best. However, an autoregressive structure, in which the previous and current test-day milk yields are assumed to be correlated, was considered more suitable in this study; it is a simpler and more appropriate covariance structure for this particular problem than is an unstructured covariance structure. Nevertheless, with the test-day approach, any of these correlation structures could be used to estimate milk loss after disease. Based on these findings, it is recommended that a repeated measures approach, rather than a single measure approach, be used to study the short-term effect of disease on milk yield.

Use of bovine somatotropin at the time of surgery for left displacement of the abomasum in dairy cows. Minnesota Dairy Practitioners Study Group

OBJECTIVE

To evaluate the effect of a single dose of recombinant bovine somatotropin (bST) on certain metabolic values, health, and milk production of dairy cows undergoing surgery for left displacement of the abomasum.

DESIGN

Blinded clinical trial.

ANIMALS

413 cows with left displacement of the abomasum.

PROCEDURE

A single 500-mg dose of bST was administered to dairy cows following surgery in field practice conditions for left displacement of the abomasum. A placebo of the same carrier without bST was administered to control cows in this blinded study. Metabolic and production responses in a short-term follow-up period were measured.

RESULTS

Blood glucose concentrations in cows 3 to 5 days after surgery were statistically higher for treated cows than for control cows. A higher proportion of treated cows had improved urine ketone test results than did controls. Significant differences in other metabolic values, health, and milk production were not detected.

CLINICAL IMPLICATIONS

Treatment of metabolically compromised cows with bST may have some positive effects, but further investigation is needed to confirm therapeutic value.

The impact of a monensin controlled-release capsule on subclinical ketosis in the transition dairy cow

An experiment was designed to examine subclinical ketosis in periparturient dairy cows and the antiketogenic effects of monensin. Subclinical ketosis was induced through a 10% feed restriction and was quantitatively determined using a blood beta-hydroxybutyrate (BHBA) threshold of 1200 mumol/L. Monensin decreased the BHBA concentration by 35% and increased the glucose concentration by 15%. No effect of monensin on milk production was detected, but rumen fermentation was altered. Monensin decreased the acetate to propionate ratio, decreased the butyrate concentration, and increased pH. The lower concentration of BHBA in blood and higher concentration of blood glucose in cows treated with a monensin controlled-release capsule decreased subclinical ketosis in early lactation cows.

Postpartum body condition score and results from the first test day milk as predictors of disease, fertility, yield, and culling in commercial dairy herds

The study used field data from a regular herd health service to investigate the relationships between body condition scores or first test day milk data and disease incidence, milk yield, fertility, and culling. Path model analysis with adjustment for time at risk was applied to delineate the time sequence of events. Milk fever occurred more often in fat cows, and endometritis occurred between calving and 20 d of lactation more often in thin cows. Fat cows were less likely to conceive at first service than were cows in normal condition. Fat body condition postpartum, higher first test day milk yield, and a fat to protein ratio of > 1.5 increased body condition loss. Fat or thin condition or condition loss was not related to other lactation diseases, fertility parameters, milk yield, or culling. First test day milk yield was 1.3 kg higher after milk fever and was 7.1 kg lower after displaced abomasum. Higher first test day milk yield directly increased the risk of ovarian cyst and lameness, increased 100-d milk yield, and reduced the risk of culling and indirectly decreased reproductive performance. Cows with a fat to protein ratio of > 1.5 had higher risks for ketosis, displaced abomasum, ovarian cyst, lameness, and mastitis. Those cows produced more milk but showed poor reproductive performance. Given this type of herd health data, we concluded that the first test day milk yield and the fat to protein ratio were more reliable indicators of disease, fertility, and milk yield than was body condition score or loss of body condition score.

Effects of milk fever, ketosis, and lameness on milk yield in dairy cows

The effects of milk fever, ketosis, and lameness were studied using data from 23,416 Finnish Ayrshire cows that calved in 1993 and were followed for one lactation (i.e., until culling or the next calving). Monthly test day milk yields were treated as repeated measurements within a cow in a mixed model analysis. Disease index variables were created to relate the timing of a disease to the measures of test day milk. Statistical models for each parity and disease included fixed effects of calving season, stage of lactation, and disease index. An autoregressive correlation structure was used to model the association among the repeated measurements. The milk yield of cows contracting milk fever was affected for a period of 4 to 6 wk after calving; the loss ranged from 1.1 to 2.9 kg/d, depending on parity and the time elapsed after milk fever diagnosis. Despite the loss, cows with milk fever produced 1.1 to 1.7 kg more milk/d than did healthy cows. Milk yield started to decline 2 to 4 wk before the diagnosis of ketosis and continued to decline for a varying time period after it. The daily milk loss was greatest within the 2 wk after the diagnosis, varying from 3.0 to 5.3 kg/d, depending on parity. Cows in parity 4 or higher were most severely affected by ketosis; the average total loss per cow was 353.4 kg. Lameness also affected milk yield; milk loss of cows diagnosed with foot and leg disorders varied between 1.5 and 2.8 kg/d during the first 2 wk after the diagnosis.

Supplement strategies for ruminants and management of feeding to maximize utilization of roughages

Principles of supplementation are discussed in respect of both, their positive and negative effects on roughage digestion and utilization by ruminants. It is pointed out that negative effects mainly occur when excessively processed concentrate is given in large quantities two times per day. This lowers rumen pH which in turn depresses cellulose digestion and intake of cellulosic feeds, leading to problems of acidosis and secondary ketosis due to off-feed conditions. To a large extent, such problems can be overcome by limited processing and feeding the concentrate mixed with the roughage. Supplements can also have positive effects by alleviating deficiencies such as nitrogen or by providing easily fermentable fiber to increase microbes for attachment to roughages. Supplements can increase microbial protein production and undegraded protein supply. It is emphasized that proper use and management of supplements can make the difference between profit and loss for small farmers.