Post partum subclinical hypocalcaemia and effects on ovarian function and uterine involution in a dairy herd.

Episodes of subclinical hypocalcaemia occurred in the first 6 weeks after calving in 6 out of 12 multiparous Friesian cows calving in the winter period and 7 out of 23 calving in the summer in a subtropical environment. In the winter calving group, there were significant (P< 0.05) decreases in mean plasma calcium concentrations (PTCa) on days 6, 27 and 36 after calving in those animals unable to maintain PTCa >2.0 mmol/L in the first 21 days. These cows had a significantly higher mean body weight and higher mean milk production than normocalcaemic cows. In the summer calving group, the seven cows with episodes of subclinical hypocalcaemia had significantly lower mean PTCa over periods of 21 and 60 days. Intervals until involution of the uterus were negatively (P< 0.05) correlated with mean PTCa over the first 21 and 30 days after calving in the winter and summer calving groups (r = -0.62 and -0.42), respectively. The mean size of the first ovulated follicles was significantly smaller in cows showing episodes of subclinical hypocalcaemia in the winter group and the mean number of ovulatory size follicles was less in these cows at 15 days (P< 0.001) (1.2 +/- 0.17 vs 2.3 +/- 0.21) and at 30 days (P< 0.03) (3.5 +/- 0.43 vs 5.2 +/- 0.54). During the first three dioestrus periods, mean plasma progesterone concentration as a function of corpus luteum area was significantly lower (P< 0.05) in the cows with episodes of subclinical hypocalcaemia in the winter group.     

Efficacy of sodium borate in the prevention of fatty liver in dairy cows

The effects of sodium borate (100 mg/kg body weight, p.o., 15 days) from a month before expected calving until a month after calving were evaluated in dairy cows susceptible to fatty liver. Cows received either sodium borate (n = 13) or no treatment (n = 10). All cows had mild fatty livers and increased plasma triglycerides and very low density lipoprotein (VLDL) concentrations at the beginning of the experiment. The control group of cows developed significant fatty liver after calving, and 2 of them had severe fatty liver associated with clinical and biochemical abnormalities. There were no clinicopathological signs related to sodium borate administration. Serum triglycerides and VLDL concentrations before calving decreased significantly at calving and after calving in controls, and they were within the normal range only after calving. There were significant alterations during the experiment in some hematological and chemical variables between groups, within period, but they were within the normal range. Unlike treated cows, serum triglycerides and VLDL concentrations correlated with liver fat content after calving in untreated cows. Our results document that sodium borate decreases the degree of fatty liver in dairy cows during early lactation.     

Liver function of dairy cows in late pregnancy and early lactation

The possibility that alterations in liver function may occur during late pregnancy as well as after calving has been investigated in healthy dairy cows and the results compared with those from non-pregnant non-lactating cows. There were significant alterations in plasma total bilirubin, glucose, total ketone body and urea concentrations, in bromsulphthalein clearance and in plasma aspartate aminotransferase and creatine kinase activities in periparturient cows compared with non-pregnant non-lactating cows. Of these, only the alterations in glucose, ketone bodies and urea concentrations and bromsulphthalein half-time and retention were markedly different before calving. The degree of fatty infiltration of the liver was significant two weeks before as well as two weeks after calving which differed from previous reports. It seems likely that the changes in the liver in dairy cows are functional and reversible and related to the metabolic demands of late pregnancy and early lactation. The results suggest that such changes in the liver occur well before calving.     

Pregnancy-specific protein B (bPSPB) and progesterone monitoring of post-partum dairy cows with placental retention

The relationship between placental retention, progesterone and pregnancy-specific protein B (bPSPB) was determined in 60 calving Holstein cows. The cows were divided into two groups with placental retention (WPR, n = 16) and no placental retention (NPR, n = 44). Every 4 days, until 60 days post-partum, blood samples were taken and the uteri were checked using ultrasonographv. The puerperal characteristics of NPR and WPR were as follows: mean days of abnormal vaginal discharge: 20.2+/-5 versus 35.6+/-7 (P < 0.01); mean intervals to uterine involution: 21.4+/-3.7 versus 27.6+/-7.6 days (P < 0.01); rate of endometritis: 25 versus 100% (P < 0.01). The mean numbers of oestrus cycles per cow were 1.75+/-0.5 versus 0.85-/+0.9 (P < 0.05) and the mean durations of the first oestrus cycle were 18+/-3.5 versus 16+/-2.1 days (P > 0.05). The mean intervals to first ovulation were 21.5+/-8.4 versus 35+/-19 days (P < 0.01). bPSPB blood concentrations were higher in the WPR group at calving with 955+/-170 versus 750+/-205 ng/ml (P < 0.01) and also during the first 32 days post-partum with 173.68+/-47.3 versus 131.0+/-29.2 ng/ml (P < 0.01). The mean bPSPB half-life was similar in the two groups: 6.9+/-2.5 versus 6.5+/-2.1 days (P > 0.05). In conclusion, it was found that placental retention was associated with a higher rate of endometritis, a lower number of cycles, longer interval to first post-partum ovulation and higher concentration of bPSPB at calving and during the post-partum period. The positive relationship between bPSPB concentrations and calf birth weight and their association with post-partum pathological events may be useful in monitoring animals presenting high concentrations at calving.     

应用烟酸,胆碱和纤维素酶对围产期奶牛脂肪肝的防治研究

给18头奶牛口服烟酸、胆碱和纤维素酶,并通过测定血液中游离脂肪酸(FFA)、谷草转氨酶(AST)和葡萄糖(Glu),监测受试牛肝脏的脂肪浸润程度,以提示上述三种药物对脂肪肝的防治效果。试验结果:预防组奶牛脂肪肝的发病率(22％)比对照组(44％)低;产后发病的平均时间(12.5d)较对照组(9.0d)晚;发病至康复时间(7.5d)也明显短于对照组(15d)。治疗组病牛肝脂肪浸润的平均治愈时间为13.6d,治愈率为100％。试验结果表明,口服烟酸,胆碱和纤维素酶对围产期奶牛脂肪肝有明显的预防和治疗作用。     

Hepatic morphology and effects of intravenous injection of sodium propionate on plasma propionate and glucose in fed and fasted dairy cattle

Sodium propionate (3 mmol/kg) was injected IV into 8 nonlactating dairy cows before and after 6 days (144 hours) of fasting. During fasting, long-chain fatty acids in plasma increased from 0.30 +/- 0.05 (SE) mM to 1.09 +/- 0.15 mM (P less than 0.05). Liver fat increased from 0.5 +/- 0.3% to 9.3 +/- 1.7% (P less than 0.05). Half-life of injected sodium propionate increased significantly (P less than 0.05) from 7.6 +/- 0.5 minutes to 10.1 +/- 1.0 minutes during fasting. Sulfobromophthalein half-life did not change significantly (3.8 +/- 0.79 minutes to 5.3 +/- 1.3 minutes). Increases in plasma glucose concentrations after propionate loading were significantly less during fasting than during feeding. Thus, the change in glucose concentration served as an indicator of hepatic conversion of propionate to glucose. Increases in glucose concentration of less than 2 mM at 30 minutes after propionate loading indicated that liver function was altered in nonlactating dairy cows.     

Total serum bile acid concentrations in dairy cows with fatty liver and liver failure

In forty-five Holstein Frisian dairy cows (1-6 weeks post partum; mean age: 5.1 +/- 1.2 years) the serum total bile acid concentrations (SBA) were measured enzymatically. In all cows a left sided abomasal displacement was corrected surgically by right side laparotomy and omentopexy three days before investigation. The liver fat content was determined in all cows histologically. Liver failure was assumed if typical clinical signs (ataxia, general depression, recumbency or coma), an increased venous plasma ammonia level (> 35 mumol/l) and a decreased plasma amino acid index (< 4.0) were found. Cows without liver failure (N = 29) were grouped according to the liver fat content as cows with mild (N = 5), moderate (N = 19) or severe hepatosteatosis (N = 5). Histological examination of liver biopsies in cows with liver failure (N = 16) revealed in twelve cases a severe fatty liver and in four cases a hydropic degeneration of the liver tissue. Although in cows without liver failure mean SBA concentrations were higher in the group with moderate (47.3 +/- 30.9 mumol/l) or severe fatty liver (32.9 +/- 21.7 mumol/l) than in that with mild lipidosis (18.0 (16.8 mumol/l), differences were not significant. The mean SBA concentration in cows with liver failure (70.5 +/- 49.5 mumol/l) was only significantly (p < 0.05) increased compared to cows with uncomplicated mild hepatic lipidosis. In conclusion, the determination of SBA concentrations is of little value in the recognition of fatty liver or even liver failure due to the considerable variance of SBA concentrations in dairy cows.     

Fat infiltration in the liver of Finnish Ayrshire cows during early lactation

The incidence and severity of fat infiltration in the liver of Finnish Ayrshire cows at 1 and 8 weeks after calving were studied. All multiparous (n = 88) and some primiparous (n = 17) cows that calved in 20 commercial milk recorded herds were investigated. The cows lost weight and a condition score decreased significantly (p < 0.05) during early lactation. Blood samples were taken at 1, 4 and 8 weeks after calving. Ketone body concentrations were highest at 4 weeks after calving. Albumin and total protein concentrations and ornithine carbamyltransferase activity in the blood increased significantly (p = < 0.05) from 1 to 8 weeks after calving. The percentage of liver fat (v/v) was significantly (p < 0.05) greater at 1 (3.9 ± 0.5 %) than at 8 weeks (1.2 ± 0.3 %) after calving. Eighty-nine of 102 cows had less than or equal to 9 % of fat in the liver (mean 2.3 ± 0.2 %), and 13 cows had more than 9% (mean 14.9 ± 1.2%) at 1 week after calving. Only blood acetoacetate and plasma aspartate aminotransferase differed significantly between the groups. In the fatty liver group the incidence rate of treated cases of ketosis was 30.8 ± 13.3 % and of parturient paresis 23.1 ± 12.2 %. In the non-fatty liver group the rates were 10.1 ± 3.2 % and 7.8 ± 2.9 %, respectively. The differences were not significant.     

Effect of nonthyroidal illness on serum thyroxine concentrations in cats: 494 cases (1988)

We reviewed the medical records of 494 cats with a variety of nonthyroidal diseases in which serum thyroxine (T4) concentration was determined as part of diagnostic evaluation. The cats were grouped by category of disease (ie, renal disease, congestive heart failure, diabetes mellitus, focal neoplasia, systemic neoplasia, hepatopathy, inflammatory bowel disease, inflammatory pulmonary disease, miscellaneous diseases, or undiagnosed disease), degree of illness (ie, mild, moderate, or severe), survival (ie, lived, died, or euthanatized), and presence or absence of a palpable thyroid gland. The mean (+/- SD) serum T4 concentrations in all 10 groups of cats, which ranged from 10.5 +/- 11.1 nmol/L in cats with diabetes mellitus to 18.7 +/- 7.8 nmol/L in cats with focal neoplasia, were significantly (P less than 0.001) lower than those of normal cats (27.0 +/- 10.4 nmol/L). The number of ill cats with low serum T4 concentrations (less than 10 nmol/L) was highest in the cats with diabetes mellitus (59%), hepatopathy (54%), renal failure (48%), and systemic neoplasia (41%). When the serum T4 concentrations in cats with mild, moderate, and severe illness were compared, mean concentrations were progressively lower (21.3 +/- 6.8, 14.8 +/- 8.1, and 6.5 +/- 5.8 nmol/L, respectively) as degree of illness increased. Severity of illness had a more significant (P less than 0.001) effect in lowering serum T4 concentrations than did disease category. Mean serum T4 concentrations in the cats that died (7.8 +/- 9.8 nmol/L) or were euthanatized (10.0 +/- 7.0 nmol/L) were also significantly (P less than 0.001) lower than those of cats that survived (15.2 +/- 8.8 nmol/L).(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma lipids in normal cows around partus and in cows with metabolic disorders with and without fatty liver

Free fatty acids, cholesterol and phospholipids in plasma were studied from 6 weeks before to 6 weeks after calving in 16 normal multiparous cows. The same plasma lipids were studied the day after calving in 20 normal primiparous cows. Ten of these were fed according to standards and the other 10 were overfed the last 3 weeks prepartum. The plasma lipids were also analysed in 16 cows with left displacement of the abomasum and fatty liver, and in 16 cows with ketosis with no or only slight fat infiltration of the liver. In the normal cows there was a rise in FFA-level and a reduction in cholesterol and phospholipids from 6 weeks before to the day after calving. Thereafter there was a reduction of FFA-level and rise in cholesterol and phospholipids. Increased feed intensity had no effect on plasma lipids at calving. The level of the plasma lipids in cows with fatty liver differed very much from the amounts in normal cows at corresponding time from calving. Cows with ketosis had high FFA-level but the amount of cholesterol and phospholipids differed very little from normal cows.     

Effects of supplementation of whole corn germ on reproductive performance, calf performance, and leptin concentration in primiparous and mature beef cows

A 2-yr study using primiparous and multiparous, spring-calving, crossbred beef cows was conducted to evaluate the effects of supplemental whole corn germ on reproductive performance, calf performance, and serum leptin concentrations. Each year, cows were blocked by age and BCS and assigned randomly to one of three treatments: PRE (n = 115) cows received 1.14 kg/d (DM basis) of whole corn germ for approximately 45 d before calving; POST (n = 109) cows were fed 1.14 kg/d of whole corn germ for approximately 45 d after calving; and control cows (n = 118) were fed similar energy and protein from dry-rolled corn (1.82 kg of DM/d) for 45 d before and after calving. Additionally, PRE cows were grouped with controls after calving, and POST cows were grouped with control cows before calving, so that corn germ-supplemented cows received the control supplement in the alternate feeding period. Cow BW (538 +/- 13 kg) and BCS (5.4 +/- 0.13) did not differ among treatments at any time during the experiment. Calf birth weight (39 +/- 2 kg), weaning weight (225 +/- 7 kg), and age-adjusted weaning weight (234 +/- 8 kg) did not differ because of dam supplementation regimen. Treatment did not affect the proportion of cows exhibiting ovarian luteal activity before the start of the breeding season (67%) or pregnancy rate (91%). The interval from exposure to bulls until subsequent calving did not differ (P = 0.16) among PRE (298 +/- 2.3 d), POST (303 +/- 2.6 d), and control (304 +/- 2.3 d) cows. Leptin concentrations did not differ among treatments and were 2.15 +/- 0.75, 1.88 +/- 0.76, and 1.91 +/- 0.75 ng/mL for control, POST, and PRE cows, respectively. Age and week relative to calving influenced leptin concentration. Primiparous cows had similar leptin concentrations to 3-yr-old and mature cows for wk -7 and -6 relative to calving, but lower (P < 0.10) concentrations than mature cows for wk -5, and lower (P < 0.05) concentrations than either 3-yr-old or mature cows for wk -4 to +7 relative to calving. Serum leptin was correlated with BCS (P < 0.0001; r = 0.35) at initiation of the feeding period and was correlated with BCS (P = 0.02; r = 0.12) and weight (P < 0.01; r = 0.14) at the completion of the supplement period, but it was not correlated with initial BW or interim BCS. Calving interval was not correlated (P > 0.12) with weekly measures of serum leptin concentration. Supplementing beef cows with whole corn germ had no effect on cow performance, calf performance, or serum leptin concentrations of cows.     

Effect of various dietary fat supplementations on liver lipid and glycogen of high-yielding dairy cows in the peripartal period

In a model experiment, Holstein-Friesian dairy cows were fed on a corn-silage-based diet supplemented with 11.75 MJ NE1 per day of calcium soaps of palm oil fatty acids (CAS) or hydrogenated triglyceride (HTG) or without fat supplementation (control). All diets were fed to the cows over a period from 21 +/- 3 days (d) prior to the expected calving to d 100 +/- 5 postpartum. On d 25 (basal sample) and d 14 prepartum as well as on d 5 and 25 postpartum liver samples were collected by percutaneous biopsy. Total lipid content, fatty acid composition and glycogen of liver tissues were determined. At d 5 postpartum, both control and CAS cows had higher liver lipid (P < 0.05) and lower glycogen (P < 0.05) concentrations than cows in the HTG group. No significant (P < 0.05) differences were detected in liver fat content among the groups at d 14 prepartum or d 25 postpartum. The glycogen concentration slightly decreased in the liver of cows in each treatment group from d 14 prepartum to d 5 postpartum; however, this decrease was more intensive in both the control and CAS groups than in the HTG group. The variations in liver lipid concentrations were accompanied by significant changes in the proportion of C16:0, C16:1n-7, C18:0, C18:1n-9, C18:2n-6 and C20:4n-6 fatty acids in the liver lipids. The results show that HTG supplementation exerted more advantageous effects on liver lipid and glycogen metabolism than did CAS supplementation.     

Iron storage disease in captive Egyptian fruit bats (Rousettus aegyptiacus): relationship of blood iron parameters to hepatic iron concentrations and hepatic histopathology.

This study evaluated the relationship between blood iron parameters and hepatic iron concentrations, and correlation of histologic findings with hepatic iron concentrations in a captive population of Egyptian fruit bats (Rousettus aegyptiacus) and island flying foxes (Pteropus hypomelanus). Blood samples were collected for complete blood counts, plasma biochemical profiles, serum iron concentrations, total iron-binding capacity, whole-blood lead concentrations, and plasma ferritin assays. Liver samples obtained by laparotomy were divided, with one half processed for histologic examination and the other half frozen and submitted for tissue mineral analysis. The histologic sections were scored by two blinded observers for iron deposition, necrosis, and fibrosis. The Egyptian fruit bats had significantly higher liver iron (mean = 3,669 +/- 1,823 ppm) and lead (mean = 8.9 +/- 5.8 ppm) concentrations than the island flying foxes (mean [Fe] = 174 +/- 173 ppm, mean [Pb] = 1.9 +/- 0.5 ppm). Hepatic iron concentrations significantly correlated with tissue lead concentrations, histologic grading for iron and necrosis, serum iron, transferrin saturation, and plasma ferritin (P < 0.001). Blood lead concentrations negatively correlated with tissue lead concentrations (P < 0.001). When the product of transferrin saturation and serum iron was greater than 51, an individual animal had a high probability of having iron overload. When the product of these two variables was greater than 90, there was a high probability that the animal had hemochromatosis. On the basis of this study, it appears that evaluation of serum iron, transferrin saturation, and plasma ferritin are useful and noninvasive methods for diagnosis of hemochromatosis in Egyptian fruit bats.     

Effects of obesity on insulin and glucose metabolism in cyclic heifers

Effects of degree of obesity on basal concentrations of insulin, glucose, thyroxine (T4), triiodothyronine (T3), estradiol-17 beta (E) and progesterone (P) were measured in serum from 50 estrous and 73 diestrous Holstein heifers and the insulin response to glucose infusion was assessed in diestrous obese (n = 7) and lean (n = 7) heifers. Basal concentrations of glucose, T4, T3, E and P were not correlated with degree of obesity, although concentrations of glucose, T4 and T3 were higher (P less than .05) at estrus than diestrus. Basal concentrations of insulin at estrus and diestrus were positively correlated (r = .6; P less than .001) with degree of obesity but this relationship was different (P less than .001) between estrus and diestrus. Furthermore, there was interaction (P less than .001) between body condition and stage of the estrous cycle only for basal concentrations (mean +/- SE) of insulin, with the difference in insulin levels (microU/ml) between 12 obese and 12 lean heifers at diestrus (11.7 +/- 1.3 vs 6.7 +/- .6; P less than .05) increasing during estrus (21.9 +/- 2.4 vs 10.8 +/- 1.3; P less than .001). Insulin response to glucose infusion was greater in obese than in lean heifers, whether determined as actual concentration (P less than .01) or as insulin response areas (P less than .05) above base-line concentrations. Obese heifers were less responsive to insulin since hyperinsulinemia and euglycemia coexisted, and because glucose fractional removal rates were similar in both groups after glucose infusion in spite of greater concentrations of insulin in obese heifers. Thus, obesity in heifers was associated with insulin resistance, basal hyperinsulinemia and greater glucose-induced secretion of insulin.     

Body weight, tick burden (Boophilus microplus), physiological parameters and reproductive efficiency of crossbred zebu cattle

Body weight at calving, degree of tick load (Boophilus microplus), rectal temperature, respiratory frequency and heart rate were evaluated and correlated to reproductive efficiency in 63 F1 Brown Swiss x Nellore milked animals reared in the tropical region of Peru. Cows were bred by free natural service, and first ovulation was estimated by progesterone measurements. The physiological parameters were registered at morning milking (04.00 to 06.00) at an average air temperature of 22.4 +/- 0.9 degrees C. The intervals from parturition to first ovulation and conception were significantly affected when the body weight at calving was lower than 400 kg (p less than 0.01). The degree of tick burden, rectal temperature (38.4 +/- 0.2 degrees C, mean +/- s.e.), respiratory rate (25.2 +/- 0.3 breaths/min) and heart rate (66.7 +/- 0.4 beats/min) were not related to post-partum reproductive efficiency. The average intervals from parturition to first ovulation and to conception were 56.3 +/- 55.5 and 77.7 +/- 46.0 days mean +/- s.d.), respectively. The fertility rate was 85.7%. The results indicate the F1 cross to be well adapted to the given environment. It remains to be determined whether higher levels of temperate blood can be used without an accompanying decrease in reproductive performance.     

Cortisol and luteinizing hormone after adrenocorticotropic hormone administration to postpartum beef cows

Cortisol and luteinizing hormone (LH) were measured in serum after the administration of adrenocorticotropic hormone (ACTH) to suckled (S) and nonsuckled (NS) beef cows. Blood was sampled on 2 consecutive days every 2 weeks for four bleeding periods starting 14 days after calving. Cows were injected with 200 IU ACTH or saline in a 2-day switchback design. Serum was collected before ACTH or saline injection and at 30-min intervals thereafter for 8 hours. Average cortisol concentrations in serum were similar in S and NS cows (6.4 +/- .6 and 6.1 +/- .8 ng/ml, respectively) after saline. Average cortisol concentrations in serum collected during an 8-hr period after ACTH on days 14, 28, 42 and 56 postpartum were 24.7 +/- 2.4, 31.8 +/- 3.5, 36.4 +/- 4.2 and 40.7 +/- .5 ng/ml, respectively, for S cows, and 31.1 +/- 2.9, 44.7 +/- 5.2, 45.0 +/- 5.7 and 46.0 +/- 5.4 ng/ml, respectively, for NS cows. Cortisol response to ACTH, measured as area under the response curve, was greater (P less than .05) in NS than in S cows. Amount of cortisol released by 200 IU ACTH was maximal by days 28 to 29 postpartum in NS cows, but the response increased gradually between days 14 to 15 and days 56 to 57 in S cows. overall, LH in serum averaged .55 +/- .08 ng/ml for S cows and .92 +/- .06 ng/ml for NS cows after saline, and .49 +/- .07 ng/ml for S cows and .94 +/- .06 ng/ml for NS cows after ACth. Although mean and peak serum LH concentrations did not differ between cows given ACTH and those given saline, the number of LH peaks and the number of cows having LH after saline. Mean serum LH concentrations were lower (P less than. 05) in S than in NS cows at 28 days postpartum. The number of LH peaks was lower (P less than .05) and the magnitude of the largest LH peak tended to be lower (P less than .06) in S cows at all sampling periods.     

Serum hormone and metabolite concentrations in fasted young bulls and steers.

The effect of dietary energy restriction on serum insulin, insulin-like growth factor I (IGF-I), growth hormone, (GH), cortisol, plasma urea nitrogen (PUN) and nonesterified fatty acid (NEFA) concentrations was examined. Angus bulls and steers (10 mo) were allotted to two groups of 12 animals and assigned a treatment order. In a switchback design, animals in order 1 were fed a high grain diet, then fasted, while order 2 animals were fasted, and then fed. Animals were allowed 60 hr to acclimate between treatments. Serum and plasma were obtained at 20 min intervals and 60 min, respectively, for 6 hr after feeding and for the last 6 hr of a 30 hr fast. Serum was assayed for insulin, IGF-I, GH, and cortisol (total and free). Plasma was assayed for PUN and NEFA. Mean insulin (ng/ml) differed between fed (.95 +/- .08) and fasted (.26 +/- .08) animals (P less than 01). Both mean total and free cortisol (ng/ml) were lower in fed (11.48 +/- .99) (1.06 +/- .12) than in fasted (17.10 +/- .93) (1.62 +/- .12) animals, respectively (P less than .01). Animals in order 1 differed in mean IGF-I (ng/ml) between fed (199.0 +/- 8.0) and fasted (116.5 +/- 7.2) treatments (P less than .01). Mean IGF-I for animals in order 2 was 146.7 +/- 7.2 in fed and 213.9 +/- 7.2 in fasted animals (P less than .01). Mean GH did not differ between treatments. Mean PUN and NEFA were higher in fasted than in fed animals (P less than .01). Except for % free cortisol (P less than .05), the hormones did not differ between bulls and steers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Furazolidone concentrations in plasma, milk and some tissues of Nubian goats

The concentrations of furazolidone (FZ) in plasma and milk were measured in goats treated orally with the drug at a dose of 10 mg kg-1 daily for 5 days. The maximum plasma concentrations obtained were 1.57 +/- 0.52 micrograms ml-1 (n = 5) 8 h after the first dose, and 2.13 +/- 0.11 micrograms ml-1 (n = 4) 6 h after the fifth dose. The maximum milk concentration was 0.88 +/- 0.32 micrograms ml-1 (n = 4) 8 h following the administration of a single dose. Using a colorimetric method, FZ was not detectable in goats' liver or muscle after the recommended therapeutic dose (10 mg kg-1, 5 days). However, using an HPLC method, the drug was detected 24 h after the treatment in the gluteal muscle and liver at concentrations of 0.26 +/- 0.01 microgram g-1 (n = 5) and 0.10 +/- 0.02 microgram g-1 (n = 5), respectively. The drug concentrations decreased significantly (P less than 0.05-0.01) at 3, 5 and 7 days after treatment, and no measurable concentrations were found after 10 days.     

Insulin-like growth factor I in follicular development and function in postpartum beef cows

The objective of this study was to determine whether nutrition affects follicular growth and(or) steroid and insulin-like growth factor I (IGF-I) concentrations in follicular fluid. Beginning 6 d after calving, Hereford-cross cows (n = 28) were fed either 14 (ad libitum) or 7 (restricted) kg.animal1.d-1 of chopped alfalfa-brome hay. Half the cows in each treatment were ovariectomized on d 20 (OVX-20) and the remaining half on d 35 (OVX-35) postpartum. Cow weight and condition score were recorded weekly, and blood was collected thrice weekly for determination of insulin, IGF-I, glucose, and free fatty acid (FFA) concentrations. At ovariectomy, follicular fluid from each follicle greater than or equal to 4 mm in diameter was aspirated for determination of IGF-I, progesterone (P4), and estradiol-17 beta (E2) concentrations. Restricted cows lost more weight after calving than did ad libitum cows (P less than .0001), although all cows lost similar amounts of body condition (time postpartum, P = .008). Concentrations of FFA were elevated (P less than .0001) in restricted cows from wk 2 through 5 after calving but did not change with time in ad libitum cows. Plasma concentrations of glucose were lower in restricted than in ad libitum cows (59.6 +/- .4 vs 61.8 +/- .4 mg/dl; P = .05), but insulin and IGF-I were similar (P greater than .10) between dietary treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of pituitary somatotropin injections on plasma insulin-like growth factor I and somatotropin profiles in growing heifers

Effects of daily injections of pituitary-derived bovine somatotropin (bST) for 6 wk were evaluated in 10 growing heifers and compared to 9 placebo-treated control animals. Bovine somatotropin was injected at 50 micrograms/kg BW each day. Body weight and growth, plasma concentrations of insulin-like growth factor I (IGF-I) and somatotropin (ST) were assessed. To measure plasma concentrations of IGF-I, we validated a RIA in which bovine plasma samples were extracted with acid-ethanol, a method that resulted in greater than 90% recovery of IGF-I. Average daily gain was similar during the first 4 wk of the experiment in both control and bST-treated groups; however, at the end of the experimental period (wk 4 and 6) ADG was greater (P less than .05) in bST-treated heifers (1.24 +/- .21 kg/d vs .75 +/- .25 kg/d). Plasma IGF-I from wk 2 to wk 6 were increased in bST-treated animals (452 +/- 97 ng/ml at wk 2; 683 +/- 106 ng/ml at wk 6) compared with controls (293 +/- 62 ng/ml at wk 2 (P less than .01) and 293 +/- 115 ng/ml at wk 6 (P less than .001). Moreover, ADG over the 6-wk experimental period was correlated with mean IGF-I concentrations determined over the same period (r = .55; P less than .01). As expected, mean plasma ST concentrations were increased in bST-injected animals from wk 1 to 6. Gel chromatographic profiles of bovine plasma exhibit a 150,000 molecular weight ST-dependent binding protein-IGF-I complex and a 30,000 molecular weight non-ST-dependent complex. This study validates a method for measuring IGF-I in cattle, and shows a positive relationship among IGF-I and ADG after ST treatment. No correlation, however, was found between plasma ST and growth performance.