This study evaluated the association of plasma gamma-glutamyl transferase (GGT) with age and nutrient-related serum or plasma biochemical components. Three hundred and five clinically healthy, 8- to 32-month-old Japanese Black beef cattle, which were raised on 5 farms in Aomori Prefecture, were used in the present study. Serum samples were collected in four stages during fattening(first stage: 9-13 months old; 69 samples, middle stage: 14-18 months old; 70 samples, late stage: 19-23 months old; 95 samples, finish stage; 24-32 months old; 71 samples). Concentrations of plasma vitamin A (VA) and beta-carotene decreased after the middle stage compared to those in the first stage. Plasma total cholesterol (TC) and GGT values increased after the middle stage, and urea nitrogen (UN) after the late stage. Serum copper (Cu) values decreased after the middle stage, while serum iron and selenium (Se) values increased in the late and finish stages. Serum Zinc (Zn) values did not show significant changes. Significant correlations of GGT concentration with age, UN, TC and Se were seen. Significant negative correlations were seen between GGT and VA as well as between GGT and beta-carotene. The relationships between elevated GGT and each of the factors, except for Cu and Zn, which are known to be affected by hepatic impairment, were examined by multiple regression analysis. The highest relative contribution ratio was 53% for age, followed by 25% for VA and 14% for UN. These results suggest that age, low plasma VA and high UN values were significantly associated with the increase in plasma GGT.

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Ursodeoxycholic acid (250mg/head/day)was administered to 10-month-old Japanese black cattle from the first day of fattening until two days before shipment, and blood chemistry and carcass quality were examined. The vitamin A level was significantly lower at 13 months old and higher at 19 months old in treated cattle than in untreated control animals. Treated cattle also showed significantly lower gamma-glutamyl transferase (GGT)at 19 and 28 months old, higher total cholesterol at 16 months old, higher triglyceride at 25 months old, lower nonesterified fatty acid at 25 months old compared to those in controls. As for the carcass quality, no significant difference was found between the two groups, but the carcass weight of treated females showed a tendency to be heavier (p=0.09). The liver disposal rate and incidence of sawdust liver were lower in treated cattle than in the control group. During the fattening period, the values of GGT were high around 19 months old and after 25 months old in the two groups. The cattle, of which liver was disposed of, showed higher values of GGT after 25 months old than in the normal liver cattle. These results suggest that administration of low dosage of ursodeoxycholic acid for a long term is effective for preventing deterioration in liver function and liver disposal.

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Effects of heat stress on blood profiles, feed intake and lactation performance during the hot season were examined in 45 dairy cows, which were either on separate feeding or on total mixed rations (TMR). Feed intake, lactation performance and blood profiles were examined once a month over a year. Accumulated 277 data sets were analyzed separately for separate feeding and TMR feeding and compared between the hot season (June to September)and optimum temperature period. In the separate feeding group, 43 data sets were obtained during the hot season, and 81 during the optimum period. During the hot season, dry matter intake(DMI, p<0.05), metabolizable energy intake (p<0.01), milk yield (p<0.01), % milk fat (p<0.05), % milk protein (p<0.001), blood glucose (p<0.001), total cholesterol (p<0.01), phospholipids (p<0.001), hematocrit (Ht, p<0.001), total protein (p<0.05), calcium (p<0.01) and aspartate aminotransferase(AST, p<0.05)were significantly lower, and betalipoprotein (BL, p<0.001)was significantly higher compared to those during the optimum period. In the TMR group, 43 data sets were obtained during the hot season, and 110 during the optimum period. Although DMI and milk yield did not differ between the two seasons, % milk fat(p<0.05), % milk protein (p<0.01), Ht (p<0.001)and AST (p<0.01)were significantly lower, and BL (p<0.001) and albumin (p<0.01)were significantly higher during the hot season compared to those during the optimum period. Thus, changes in blood profiles were more frequently observed in cows on separate feeding than in those on TMR feeding. As the separate feeding system resulted in decreased DMI and milk yield during the hot season and TMR feeding did not, the effects of heat stress observed in blood profiles seem to be the results of altered feed intake and lactation performance.

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To determine the significance of adenosine deaminase(ADA)in the bovine colostrum, first, colostrum and ordinary milk samples were collected from 35 healthy adult Holstein cows and analyzed for ADA activity. The mean ADA activity was 11.9±2.9 IU/ℓ in the colostrum, which was significantly higher than 0.03±0.01 IU/ℓ in the ordinary milk. In the second experiment, 11 healthy adult Holstein cows were examined for serum ADA activity and by peripheral lymphocyte transformation(LT)test during the peripartum period. Whey ADA and LT were also examined for the colostrum. The results were compared between mastitis(M)and non-mastitis(NM) groups diagnosed by the modified California mastitis test. Serum ADA activities in the M group tended to be higher than those in the NM group. The whey ADA activity in the colostrums was 23.0±5.1 IU/ℓ in the M group and 13.5±1.7 IU/ℓ in the NM group with a significant difference between these groups. LT in the peripheral blood in the NM group tended to be lower at parturition, whereas that in the M group remained high even at parturition. LT in the colostrum in the M group was significantly higher than that in the NM group. Cows with high LT also had high whey ADA activities in the colostrums. These results suggest a possibility that ADA activity might be correlated with the number of CD4⁺ T cells in the colostrums. Because measurement of the whey ADA activity is very simple and rapid, colostrum ADA activity seems to be a potential indicator of immune status in the colostrums.

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A 7-year-old Holstein cow with urovagina experienced an embryonic death between Day 30 and Day 39 of gestation after embryonic transfer. To investigate the cause of the embryonic death, we carried out a blood test, ultrasound imaging and bacteriological examination of uterine fluid and urine. As a result, numerous Enterococcus faecium were isolated from both the uterine fluid and urine. It has been reported that the genus Enterococcus is present in the normal vaginal flora and that Enterococci can cause uterine infection, but the infection has not been associated with endometrial lesions. In the present case, however, enterococcal growth in the uterus was likely a contributing factor to the embryonic death, because numerous Enterococcus faecium was found in the uterus 2 days after embryonic death,although the uterus was supposed to be germfree during pregnancy. These results suggest that uterine infection with normal vaginal bacteria may cause an embryonic death. Urovagina seemed to have contributed to the infection, but we could not confirm this by further analyses. Since only a few reports are available on the relationship between embryonic death and uterus bacterial infection in cows with urovagina, it is important to continue the investigation.

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