Etiology of lipid-related metabolic disorders in periparturient dairy cows

Metabolic and yield responses of multiparous Holstein cows to prepartum rumen-undegradable protein

The effects of concentration of rumen-undegradable protein (RUP) in prepartum diets on performance and metabolic measures were determined. Pregnant, nonlactating cows were assigned to one of three dietary treatments that differed in concentrations of crude protein and RUP. The crude protein and RUP percentages (dry matter basis) in the diets were 11.7 and 3.1%, 15.6 and 6.8%, and 20.6 and 10.6%, which were identified as low, medium, and high protein diets, respectively. Dietary treatments were initiated 6 wk prior to expected calving date and were fed until parturition. All cows were fed similar postpartum diets through wk 10 of lactation. Prepartum intakes of dry matter and rumen-degradable protein were similar among treatments. Yields of milk, protein, and fat were not affected by prepartum RUP. Concentrations of plasma urea N in cows fed the medium and high protein diets were elevated during the prepartum period even though intakes of rumen-degradable protein were similar for cows on all treatments. Cows fed the medium and high protein diets had greater prepartum concentrations of Val, Ile, and Leu but not other essential amino acids in plasma. Dietary treatments did not affect prepartum or postpartum contents of triglycerides in liver or plasma nonesterified fatty acid concentrations. Thus, supplemental RUP fed to cows for 6 wk prepartum affected protein metabolism but not measures of energy metabolism.

Use of hydrochloric acid as a source of anions for prevention of milk fever

Diets that contain high amounts of K induce milk fever by alkalinizing the blood of the cow, reducing the ability of homeostatic mechanisms to maintain normal blood concentrations of Ca. The addition of anions to the diet induces metabolic acidosis, which counteracts the alkalinizing effect of the high cation diets commonly fed to cows. Currently, anions are usually added as anionic salts, such as CaCl2 or MgSO4, and the pH of urine is often monitored to assess the degree of metabolic acidification resulting from the addition of anions to the diet. An alternative source of anions is HCl. In Experiment 1, the addition of HCl to the diet of cows that were not pregnant and not lactating significantly reduced the pH of urine and blood within 24 h. After HCl was removed from the diet, the pH of urine returned to baseline levels within 48 h. In Experiment 2, the inclusion of HCl into the prepartum ration of Jersey cows entering the third or greater lactation significantly reduced the incidence of milk fever from 63% of control cows to 11% of the treated cows and also reduced the degree of hypocalcemia that was experienced by the cows during the periparturient period. Plasma Ca concentrations at 0.5 d after calving were 5.33 +/- 0.52 and 6.69 +/- 0.51 mg/dl in the control and the HCl-treated cows, respectively. In Experiment 2, the prepartum consumption of the ration with HCl was greater than the consumption of the control ration. In liquid form, HCl remains dangerous to handle and corrosive to machinery. Commercial preparations of HCl mixed into common feed ingredients as a premix could offer an inexpensive and palatable alternative to anionic salts as a means of controlling the incidence of milk fever in dairy cows.

The effect of ruminal bypass lysine and methionine on milk yield and composition of lactating cows

Fifty-six multiparous Holstein cows were assigned at 3 wk prepartum to rations based on grass silage with 1) corn distillers grains to provide 86 and 90% of estimated required metabolizable Lys and Met, respectively; 2) a blend of blood meal, fish meal, and meat and bone meal as amino acid (AA) sources to provide 112 and 103% of required metabolizable Lys and Met, respectively; 3) ruminally protected Lys and Met added as a top-dressing to ration 1 to provide 27 g/d of Lys and 8 g/d of Met as available AA at the duodenum postpartum; and 4) ruminally protected AA for 8 wk postpartum as a top-dressing to ration 1 to provide 40 g/d of Lys and 13 g/d of Met as available AA at the duodenum. Cows fed rations 3 and 4 were offered 13.5 g/d of duodenally available Lys and 4 g/d of duodenally available Met for 3 wk prepartum. The total length of the study was 43 wk. Cows fed ration 4 consumed 3 to 4 kg more dry matter than did cows fed the other three rations, and milk yield and the percentage of milk protein and fat were significantly increased during the first 8 wk of lactation. In early lactation, cows fed ration 3 had a greater milk fat percentage but similar dry matter intake, protein percentage, and yield of 4% fat-corrected milk compared with cows fed ration 2. The concentrations of blood serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, triglyceride, and nonesterified fatty acids were lower for cows fed ration 4 during the first 8 wk of lactation than they were for cows fed the other three rations. The mammary arteriovenous difference of whole blood AA indicated that Met along with His and Arg may be the most limiting AA for milk yield.

Effect of long-chain fatty acids on triglyceride accumulation, gluconeogenesis, and ureagenesis in bovine hepatocytes

A relationship between increased lipid concentration in the liver and reduced hepatic function has been suggested; however, there is little direct evidence of change in specific hepatic functions. Hepatocytes were obtained from ruminating calves and were incubated as monolayers for 36 h. The media contained a mixture of nonesterified fatty acids (NEFA) at 0, 0.5, 1.0, and 1.5 mM NEFA with molar proportions of 0.435 oleate, 0.319 palmitate, 0.144 stearate, 0.049 linoleate, and 0.053 palmitoleate. Ureagenesis or gluconeogenesis was measured from 48 to 51 h after plating using hepatocytes that had only previous (12 to 48 h), only concurrent (48 to 51 h), or previous and concurrent (12 to 51 h) exposure to NEFA. A previous 36-h exposure to NEFA caused cell triglyceride accumulation, yielding triglyceride concentrations that corresponded with liver that is clinically described as normal to moderately fatty. Previous, prolonged exposure to NEFA reduced ureagenesis and increased gluconeogenesis. Concurrent exposure to NEFA did not significantly affect gluconeogenesis or ureagenesis and did not alter the residual effect of prolonged incubation with NEFA. Reduced ureagenesis was related to increased cell triglyceride accumulation independently of other direct NEFA effects. Decreased ureagenic capacity may play a role in the morbidity associated with periparturient fatty liver in dairy cows.

Relationship of triglyceride accumulation to insulin clearance and hormonal responsiveness in bovine hepatocytes

The accumulation of triglycerides in the liver has been associated with reduced hepatic function; however, direct evidence that fat accumulation causes decreased liver function is lacking. Hepatocyte monolayers isolated from ruminating calves with an initial low triglyceride concentration were either loaded or not loaded with triglycerides by incubation with 1.5 or 0 mM exogenous nonesterified fatty acids from 12 to 48 h after plating. Basal rates of synthesis of albumin and protein were not affected by triglycerides in the cell. Inclusion of insulin and glucagon from 12 to 72 h after plating increased rates of albumin and protein synthesis. Hepatocytes loaded with triglycerides were less sensitive to the hormonal stimulation of albumin and protein synthesis than were normal hepatocytes. Insulin clearance rates were also lower in hepatocytes loaded with triglycerides than in normal hepatocytes. Decreased insulin clearance and hormonal control of protein synthesis could contribute to the etiology of metabolic disorders that are associated with periparturient fatty liver in dairy cows.

Dry cow diet, management, and energy balance as risk factors for displaced abomasum in high producing dairy herds

The objective of this study was to determine prepartum risk factors for displaced abomasum. The design was a prospective study of 1170 multiparous Holstein cows from 67 high producing dairy herds in Michigan. Each farm was visited four times within a 6-wk period. At each visit, data on nutrition and management were collected. All multiparous cows within 35 d of projected calving were assigned a body condition score, and blood was sampled to determine the concentration of nonesterified fatty acids in plasma. A multivariable linear regression model was used to determine risk factors associated with the incidence of displaced abomasum during lactation on a herd basis. A multivariable logistic regression model with random effect was used to determine risk factors for displaced abomasum on an individual cow basis. Significant risk factors for displaced abomasum included a negative energy balance prepartum (as estimated from plasma nonesterified fatty acids), a high body condition score, suboptimal feed bunk management prepartum, prepartum diets containing > 1.65 Mcal of net energy for lactation/kg of dry matter, winter and summer seasons, high genetic merit, and low parity.

Effects of nonfiber carbohydrate and niacin on periparturient metabolic status and lactation of dairy cows

Fifty Holstein cows and 25 Holstein heifers were used in a randomized complete block design. Treatments were a standard nonfiber carbohydrate diet beginning at 19 d prepartum, a high nonfiber carbohydrate diet beginning at 19 d prepartum, a standard nonfiber carbohydrate diet plus niacin (12 g/d) beginning at 19 d prepartum, a high nonfiber carbohydrate diet plus niacin beginning at 19 d prepartum, and a standard nonfiber carbohydrate diet beginning at 19 d prepartum plus niacin beginning at 14 d postpartum. Treatments were applied through 40 wk postpartum. Niacin did not significantly affect production parameters or blood and liver metabolites. Prepartum intakes of dry matter and energy and energy balance were greater for cows and heifers fed the high nonfiber carbohydrate diets. Plasma glucose concentrations tended to be significantly higher, and nonesterified fatty acids and beta-hydroxybutyrate concentrations were significantly lower, when animals were fed diets that were high in nonfiber carbohydrates. Diets containing high nonfiber carbohydrates increased concentrations of liver glycogen and tended to reduce concentrations of liver triglyceride. Milk production tended to be higher, milk fat percentage tended to be lower, and milk protein percentage and production were significantly greater when diets that were high in nonfiber carbohydrates were fed. An increase in dietary nonfiber carbohydrates improved the metabolic parameters during the transition period and improved lactation performance.

Effects of chain length and unsaturation of fatty acid mixtures infused into the abomasum of lactating dairy cows

Six cows were utilized in a 6 x 6 Latin square design with 21-d periods to determine effects of the postruminal profile of fatty acids on dry matter (DM) intake, milk yield and composition, nutrient digestibilities, and plasma metabolites. Treatments were abomasal infusions of 1) control [168 g/d of meat solubles (carrier for fatty acids) plus 10.6 g/d of Tween 80 (emulsifier)], 2) control plus 450 g/d of mostly saturated fatty acids, 3) control plus 450 g/d of palm oil fatty acids low in linoleic acid, 4) control plus 450 g/d of palm oil fatty acids, 5) control plus 450 g/d of soybean oil fatty acids, and 6) control plus 450 g/d of soybean oil fatty acids high in palmitic acid. Treatments 2, 3, 4, and 6 contained similar ratios of C16 to C18 fatty acids. Infusion of soybean oil fatty acids or soybean oil fatty acids high in palmitic acid decreased intakes of DM, organic matter, crude protein, acid detergent fiber, neutral detergent fiber, gross energy, and total fatty acids and tended to decrease yields of milk and fat-corrected milk compared with the infusion of mostly saturated fatty acids. Infusion of palm oil fatty acids low in linoleic acid or palm oil fatty acids decreased milk fat percentage compared with other treatments. Ruminal characteristics and apparent digestibilities of DM, organic matter, crude protein, acid detergent fiber, neutral detergent fiber, energy, total fatty acids, and total C18 fatty acids were not different. Infusion of fatty acids increased concentrations of cholesterol in plasma. The amount of unsaturated fatty acids passing into the small intestine may influence responses of dairy cows to supplemental fat.

Hepatic carnitine palmitoyltransferase activity in cattle

A fluorometric assay for the determination of hepatic carnitine palmitoyltransferase (CPT) activity was slightly modified for use with cattle samples. With this assay, the Km value was 0.56 +/- 0.10 mM with respect to L-carnitine (mean +/- SD, n = 4) and was 9.6 +/- 2.2 microM (n = 3) with respect to palmitoyl-CoA. The average hepatic CPT activity was 33.6 +/- 2.0 mumol CoASH/min/g protein in 38 healthy cattle and was similar in both sexes and among breeds. Hepatic CPT activity showed no correlation with serum phospholipid, free fatty acid, triglyceride or total cholesterol concentrations.

The association of serum nonesterified fatty acids and cholesterol, management and feeding practices with peripartum disease in dairy cows

A prospective study was conducted to determine the relationship of serum nonesterified fatty acids (NEFA) and cholesterol concentrations and herd management practices to the occurrence of metritis, mastitis and retained placenta in Holstein cows in Michigan. Serum samples were collected once prepartum and once postpartum from 257 cows. Animals were under observation for disease occurrence from the date of calving until 3 months postpartum. Metabolic variables used were (1) prepartum only; (2) postpartum only; (3) the NEFA/cholesterol ratio for both pre- and postpartum samples. Management variables included maternity management, feed management, and factors such as season and parity. Multivariable logistic models with random-effect terms to account for the herd effect were used for data analysis. Results showed that: (1) metabolic events associated with energy insufficiency-increased fat mobilization and serum lipoprotein metabolism-were related to increased risk of metritis and retained placenta; (2) higher energy consumption during the last weeks of the dry period might reduce disease risk at parturition; (3) serum NEFA and cholesterol concentrations have potential as indicators of disease risk in dairy cows.

Physiological changes at parturition and their relationship to metabolic disorders

Most of the metabolic diseases of dairy cows-milk fever, ketosis, retained placenta, and displacement of the abomasum-occur within the first 2 wk of lactation. The etiology of many of those metabolic diseases that are not clinically apparent during the first 2 wk of lactation, such as laminitis, can be traced back to insults that occurred during early lactation. In addition to metabolic disease, the overwhelming majority of infectious disease, in particular mastitis, becomes clinically apparent during the first 2 wk of lactation. Three basic physiological functions must be maintained during the periparturient period if disease is to be avoided: adaptation of the rumen to lactation diets that are high in energy density, maintenance of normocalcemia, and maintenance of a strong immune system. The incidence of both metabolic and infectious diseases is greatly increased whenever one or more of these physiological functions are impaired. This paper discusses the etiological role of each of these factors in the development of common diseases encountered during the periparturient period.

Hepatic gene expression of apolipoprotein B100 during early lactation in underfed, high producing dairy cows

The hepatic gene expression of apolipoprotein B, the major protein of very low density lipoproteins in plasma, was studied using 8 Holstein x Friesian cows during the first 12 wk of lactation. Cows were fattened during gestation and were underfed just after parturition to increase fat mobilization and subsequent hepatic steatosis. Intracellular concentrations of apolipoprotein B and apolipoprotein B mRNA and control parameters (albumin, total lipids, RNA, and proteins) were determined in liver samples obtained by biopsy from each cow on four occasions at 1, 2, 4, and 12 wk after calving. Results were compared with those obtained from 5 dry cows in late pregnancy and 4 dry nonpregnant cows. The hepatic concentration of apolipoprotein B was lower (approximately 25%) during wk 1, 2, and 4 after calving, a period of intense liver steatosis (44.2 to 95.7 mg of triglycerides/g of fresh tissue), than for nonsteatotic dry cows (pregnant or nonpregnant); hepatic concentrations were also lower than those during wk 12. In contrast, hepatic concentrations of mRNA coding for apolipoprotein B, total proteins, RNA, and albumin did not vary significantly during early lactation. These results suggested that synthesis of apolipoprotein B during early lactation is specifically regulated at a posttranscriptional level by a decrease in the rate of translation, or by a higher rate of intracellular degradation of apolipoprotein B, or both.

Plasma and liver alpha-tocopherol in dairy cows with left abomasal displacement and fatty liver

Thirty dairy cows with left abomasal displacement (LAD) and 14 healthy control cows were studied to assess the status of the natural antioxidant vitamin E, lipid peroxidation in the liver (malondialdehyde-formation) and its relationship to hepatic lipidosis. Blood concentrations of alpha-tocopherol, aminotransferase, glutamin dehydrogenase, free fatty acids, beta-hydroxybutyrate and glucose were determined. alpha-tocopherol, tryglyceride, glycogen and malondialdehyde (MDA) in wer liver tissue samples were examined. The dietary alpha-tocopherol intake and its plasma changes in LDA cows were also investigated. Cows were divided into four groups according to their liver triglyceride contents (< 20; 20-80; > 80 mg/g of fresh tissue; and control groups). The lowest plasma vitamin E and the highest liver vitamin E levels were found in cows with highest hepatic triglyceride content. The highest increase in plasma alpha-tocopherol within 5 days was seen in cows with the lowest liver triglyceride (P < 0.01). The liver triglyceride was positively correlated with liver MDA (r = 0.38; P < 0.05) and negatively with plasma alpha-tocopherol (r = -0.41; P < 0.01).

Production, digestion, and hepatic lipid metabolism of dairy cows fed increased energy from fat or concentrate

Eight Holstein cows (mean = 52 DIM) were used in a replicated Latin square design (28-d periods) to determine the effects of source and amount of dietary energy on hepatic lipid metabolism. Diets were 1) low concentrate without supplemental fat (1.6 Mcal of NEI/kg), 2) low concentrate with supplemental fat (1.7 Mcal/kg), 3) high concentrate without supplemental fat (1.7 Mcal/kg), and 4) high concentrate with supplemental fat (1.8 Mcal/kg). Intakes of DM and digestible energy were greatest for diets 2 and 3. Milk production, efficiency, and milk CP production were not different among diets. Milk fat percentage and production were increased by supplemental fat and decreased by high concentrate. Contents of CP, true protein, and casein in milk were decreased by supplemental fat and increased by high concentrate. Digestibility of fatty acids was decreased by either supplemental fat or high concentrate. Concentrations of NEFA and somatotropin in plasma were increased, and concentration of IGF-I was decreased, by supplemental fat; NEFA, BHBA, and IGF-I were decreased by high concentrate. In vitro rates of peroxisomal beta-oxidation and esterification of palmitate and concentrations of total lipid and triglycerides in liver were not different among diets, but glycogen content was increased by high concentrate. The rate of total beta-oxidation of palmitate in liver slices tended to be increased by supplemental fat; total metabolism of palmitate was increased by supplemental fat and tended to be increased by high concentrate. Supplemental fat may affect hepatic lipid metabolism in dairy cows; effects of dietary fat during the periparturient period deserve investigation.

Effects of diets containing tallow and soybean oil with and without cholesterol on hepatic metabolism of lipids and lipoproteins in the preruminant calf

The effects of long-chain fatty acids (230 g/kg of dietary DM) from tallow and from soybean oil, with or without cholesterol (10 g/kg of dietary DM), on hepatic lipid contents and on in vivo hepatic production rates of lipids and lipoproteins were investigated in 22 preruminant male calves fitted with chronic catheters and with electromagnetic blood flow probes implanted in the hepatic vessels. Diets containing soybean oil and soybean oil with cholesterol led to the development of triglyceride infiltration in the liver and to higher apparent hepatic secretion of very low density lipoproteins than did diets containing tallow or tallow with cholesterol. Addition of cholesterol to diets favored accumulation of low density lipoproteins in plasma and the net apparent secretion of these particles by the liver, especially for the diet containing soybean oil with cholesterol. Regardless of the diet, calf liver clearly removed large high density lipoproteins of type 1 that were rich in cholesteryl esters but secreted heavy high density lipoproteins that were rich in proteins. The intensity of removal of high density lipoproteins of type 1 by the liver depended on the plasma concentration of these particles, probably by mass action. This removal did not prevent the accumulation of high density lipoproteins of type 1 in plasma, such as it did in calves fed soybean oil.

Nutrition during the dry period and hepatic lipid metabolism of periparturient dairy cows

From dry-off until 7 d before expected parturition date, 30 Holstein cows were fed a low energy diet (control) to maintain body condition or high energy diets (high fat or isocaloric high grain) to attempt to increase body condition. After parturition, all cows were fed a common lactation diet. Body condition was unchanged for cows fed control or high grain diets, but was decreased for cows fed the high fat diet because DMI was decreased. Cows fed the high fat diet during the dry period had decreased triglyceride accumulation in the liver at 1 d postpartum, which was accompanied by lowered plasma NEFA, increased peroxisomal beta-oxidation of palmitate by liver homogenates, and decreased esterification of palmitate by liver slices. During the last 3 wk prepartum, cows fed the high fat diet had lower glycogen and higher acid-soluble carnitine in liver, higher concentrations of NEFA and bST in plasma, higher ratio of triiodothyronine to thyroxine in plasma, and lower concentrations of insulin and thyroxine in plasma than did cows fed the high grain diet. After parturition, cows fed the high fat diet during the dry period had decreased percentage and production of milk fat; differences among treatments were not significant for DMI, body condition, milk production, or milk protein. Periparturient lipid metabolism was altered significantly in cows fed a high fat diet during the dry period, although diet composition and nutrient intakes were confounded.

Effects of dietary fat with or without nicotinic acid on nutrient flow to the duodenum of dairy cows

Four Holstein cows, fitted with ruminal and duodenal cannulas, were utilized in a 4 x 4 Latin square design to investigate the effects of supplementing nicotinic acid to diets that contained 35% alfalfa haylage, 15% corn silage, and either 50% of a low fat concentrate or 10% whole raw soybeans and 40% of a high fat concentrate containing tallow. Treatments in a 2 x 2 arrangement were 1) low fat, no supplemental nicotinic acid; 2) low fat, 12 g/d of nicotinic acid; 3) high fat, no supplemental nicotinic acid; and 4) high fat, 12 g/d of nicotinic acid. The DMI and OM apparently and truly digested in the rumen and apparently digested postruminally were not different among treatments. Addition of fat to the diet decreased the concentration of total VFA in ruminal fluid but did not alter the molar proportions of any of the VFA; supplementation of nicotinic acid tended to decrease the molar proportion of acetate. Amounts of NAN, microbial N, nonammonia nonmicrobial N, and AA that flowed to the duodenum were similar among diets. The concentration of urea N in plasma decreased, and concentrations of cholesterol and triglycerides increased, when cows were fed supplemental fat. Milk composition and production of milk, 4% FCM, and milk components were not altered by addition of fat or nicotinic acid to the diet. Supplementation of fat or nicotinic acid to diets of dairy cows was not beneficial in this experiment.

Effect of propylene glycol supplementation around parturition on milk yield, reproduction performance and some hormonal and metabolic characteristics in dairy cows

Thirty-nine multiparous Holstein cows were used to measure the effect of propylene glycol treatment around parturition on milk yield, reproductive efficiency and some hormone and metabolite concentrations. Cows were assigned randomly to control (n = 19) or propylene glycol treated (n = 20) groups. Propylene glycol (300 g) was administered directly mixed with the diet from day 10 prior to the expected calving date until parturition (day 0) and orally after dilution in 1 l water on days 3, 6, 9 and 12. Blood samples were collected on days -20, -5, 0, 3, 10, 25 and 50 while milk samples were taken weekly until 13 weeks post partum. Body condition scores, recorded on days -20, 15 and 50, were not affected by propylene glycol administration. Propylene glycol did not significantly affect milk yield or composition but linear somatic cell score measured from the first 13 weeks post partum was reduced by propylene glycol administration (P < 0.01). Moreover, propylene glycol reduced milk urea (-25 mg/l, P < 0.05), especially during the first 9 weeks post partum. Plasma insulin concentrations were similar in both groups during the experiment while insulin-like growth factor I (P < 0.05) and insulin-like growth factor-binding protein 3 (P < 0.001) levels were higher on days 10, 25 and 50 post partum in the propylene glycol group. Propylene glycol administration decreased plasma non-esterified fatty acid concentrations (P < 0.05 to P < 0.01) but increased total cholesterol levels (P < 0.01) after parturition while 3-hydroxybutyrate levels were unaffected by the treatment. Changes in the hormone and metabolic concentrations after propylene glycol administration in the last few days of gestation and the first week of lactation seem to indicate that energy balance in the treated group was probably more positive than in the control group. There was also evidence that propylene glycol administration prevented fatty liver syndrome and hastened the resumption of oestrous cycles (P < 0.001).

Effects of fenprostalene and estradiol-17 beta benzoate on parturition and retained placenta in dairy cows and heifers

It was hypothesized that a high dose of estrogen in conjunction with a long-acting PGF2 alpha analog would synchronize parturition within a narrow time frame and reduce the incidence of retained placenta. On d 276 of gestation, 14 animals (9 cows and 5 heifers) per group received a placebo (group A), 1 mg of fenprostalene (group B), 50 mg of estradiol-17 beta benzoate (group C), or both (group D). Treatment with estradiol-17 beta benzoate increased serum concentrations of estradiol-17 beta from 228 pg/ml at treatment to 642 and 683 pg/ml at 24 h posttreatment for groups C and D, respectively. Concentration of estradiol-17 beta in group A increased gradually to 526 pg/ml at 24 h prepartum. Progesterone concentrations were reduced by fenprostalene but not by estradiol-17 beta benzoate. Estradiol-17 beta benzoate did not reduce incidence of retained placenta in animals treated with fenprostalene (group B vs. group D) but tended to reduce incidence in uninduced animals (group A vs. group C). Thus, short-term elevation of estradiol-17 beta to normal prepartum concentrations did not regress the corpus luteum, induce parturition, or reduce incidence of retained placenta. However, elevation of estradiol-17 beta for longer periods might enhance placental separation. Conversely, fenprostalene induced calving approximately 2 d after treatment. In this study, 90% of animals treated with fenprostalene calved within a 20-h period, but with a high incidence of retained placenta.

Peripartum liver triglyceride and plasma metabolites in dairy cows

Nine pregnant, nonlactating cows were used to monitor liver triglycerides before and after parturition. Estimates were made of the contribution of depressed feed intake and parturition to plasma NEFA concentrations and development of fatty liver. Liver biopsies and plasma samples were obtained on d 19, 10, 5, 3, and 1 prior to calving and on d 1, 7, 14, and 21 after calving. Depression of DMI started on d 2 prior to calving and was 40% of DMI on d 3 prior to depression of feed intake. Elevation of plasma NEFA concentrations started prior to DMI depression, on d 5 before parturition. Liver triglyceride infiltration did not occur until the concentration of plasma NEFA was maximized on d 1 after calving. This result implicated the acute rise in NEFA at calving as a contributing factor to triglyceride accumulation in the liver. The increasing plasma glucose and decreasing plasma BHBA prior to calving may have reflected metabolic changes toward gluconeogenesis. Liver glycogen decreased 70% during the final 19 d prior to calving. Hepatic triglyceride infiltration (7.7% DM basis) on d 1 post-partum and duration of DMI depression prepartum were less severe than those observed in previous studies. Frequent liver biopsies did not affect DMI.

Effect of prepartum propylene glycol administration on periparturient fatty liver in dairy cows

Plasma glucose concentration during late gestation was thought to be important for the development of fatty liver near parturition. Thirteen multiparous cows were given a 1-L oral drench of propylene glycol once daily beginning 10 +/- 3.6 d prepartum until parturition. Eleven control cows received a 1-L water drench. Plasma glucose increased following propylene glycol administration. Plasma NEFA concentration was 403 and 234 microM, and plasma insulin concentrations were .354 and .679 ng/ml, for control cows and cows treated with propylene glycol measured from 1 to 7 d prepartum. Plasma NEFA tended to be lower in cows treated with propylene glycol from 1 to 21 d postpartum. Prepartum propylene glycol administration reduced hepatic triglyceride accumulation by 32 and 42% at 1 and 21 d postpartum, respectively. Prepartum plasma BHBA was reduced during propylene glycol administration. Prepartum plasma glucose, NEFA, BHBA, and insulin were strongly correlated with liver triglyceride at 1 d postpartum (r = -.49, .45, .36, and -.49, respectively). Pre- and postpartum DMI were not affected by treatment. Milk production and composition measured through 21 d postpartum were not different between groups.