Effects of estradiol benzoate and estrus on N-acetyl-beta-D-glucosaminidase activity and somatic cell concentration in milk

Effect of steroid hormones on the innate immune response induced by Staphylococcus aureus in the goat mammary gland

The objective of this study was to compare the dynamics of innate immune components after intramammary infusion of Staphylococcus aureus (SA) under conditions of high oestrogen and high progesterone in goats. In one group ("E-group"), controlled internal drug release (CIDR) devices were inserted intravaginally from days -11 to -4. Prostaglandin F2α was administered immediately after removal of the CIDR device at day -3, and then oestradiol benzoate (E) was injected intramuscularly once a day from days -2 to 3. Heat-inactivated SA was then administered via intramammary infusion to the left udder at day 0, whilst only saline was infused to the right udder as a control. In a second group ("P-group"), CIDR devices were inserted intravaginally from days -3 to 7 and SA was infused at day 0 in the same way as in the E-group. The milk yield and the concentration of innate immune components (somatic cell count (SCC), lactoferrin (LF), S100A7 and goat ß-defensin 1 (GBD-1)) in the milk were measured. Milk yield decreased drastically in both SA and control udders in the E-group, whereas the P-group exhibited increased milk yield in both SA and control udders. SCC increased after SA infusion in both E- and P-groups, although it was higher in the E-group than in the P-group. There was no significant change in LF concentration in the E-group, but a decrease was observed in the P-group. Concentrations of S100A and GBD-1 were significantly increased after SA infusion in the E-group but not in the P-group. These results suggest that E enhances the innate immune response induced by SA in the goat mammary gland. This effect may be due to the reduction in milk yield and upregulation of innate immune components.

The effect of estrus synchronization treatments on somatic cell count of transitional-anestrus Awassi ewes' milk

Fifty-three transitional-anestrus Awassi ewes, randomly assigned to three groups: fluorogestone acetate (FGA, n = 18), FGA-Prostaglandin (FGA-PGF, n = 18) and control (n = 17), were used to examine the effect of estrus synchronization protocols and steroid hormones concentrations on milk somatic cell count (SCC). Intravaginal FGA sponge was inserted for 13 days and 600 IU equine chorionic gonadotropin was administered for ewes of FGA and FGA-PGF groups at the time of sponge removal (day 0). In addition, 10 mg was administered to ewes of FGA-PGF group on day 0. Blood and milk samples were collected from all ewes on days -13, -6, 0, 1, 2, 7 and 14. Estradiol had significant positive correlation with the SCC during the periods of sponge insertion (P = 0.015, r = 0.235) and within two days (P = 0.063 r = 0.23) after sponge removal with no correlation with SCC of both udder halves during the luteal phase. Progesterone concentrations, on the other hand, had a significant positive correlation (P < 0.001; r = 0.420) with the SCC of both udder halves during the luteal phase of the experiment, but not during the periods of sponge insertion and expected estrus. SCC returned under the influence of endogenous progesterone on days 7 and 14 to pre-synchronization values. In conclusion, sheep milk SCC is affected significantly with induction of estrus and steroid hormones concentrations. However, peak SCC recorded during estrus was far below the upper limit of the current standard for normal milk. With the current standards for SCC of 1,000,000/ml as legal limit for abnormal milk control programs in sheep, estrus synchronization programs and the estrus status should not be considered when bulk-tank milk SCC is being investigated, but should be considered during the process of setting new standards.

The effect of estrus synchronization treatment on somatic cell count of transitional-anestrus local-Damascus cross breed goats' milk

An experiment was conducted to examine the effect of estrus synchronization protocols and steroid hormones concentrations on somatic cell count (SCC) of transitional-anestrus local-Damascus cross goats' milk. Fifty-six goats (2-4-year old) were randomly assigned to three groups: fluorogestone acetate (FGA, n = 19), FGA-Prostaglandin (FGA-PGF, n = 19) and control (n = 18) groups. Intravaginal sponge containing 40 mg FGA was inserted for 13 days and an injection of 600 IU equine chorionic gonadotropin (eCG) was administered for goats of FGA and FGA-PGF groups at the time of sponge removal (day 0). In addition, goats of FGA-PGF group were injected with 10 mg dinoprost tromethamine (PGF2alpha) on day 0. Five fertile local-Damascus cross bucks were turned-in with all goats on day 0. Blood and milk samples were collected from all goats on days -13 (beginning of experiment), -6, 0, 1, 2, 7, 13 and 20 (end of the experiment). Four-year old and second-parity goats had significantly higher (p < 0.05) SCC of both udder halves than 2- and 3-year old and first-parity goats, respectively. There was a significant effect (p < 0.05) for treatment and number of kids born in the last kidding season on SCC of both udder halves. Neither estradiol nor progesterone concentrations were correlated with SCC in goats in this experiment. The SCC of both udder halves and left udder halves in goats of the control and FGA groups, respectively, increased significantly (p < 0.05) after sponge removal and buck introduction when compared with day 0, with no differences in the FGA-PGF group. This increase in SCC of the control and FGA groups coincided with peak estrus behavior. However, SCC was far below the upper limit of the current standard for normal milk. In conclusion, induction of estrus with progestagen based programs and buck introduction may cause temporary significant increase in SCC. However, the SCC values during this period of temporary increase were still in the range of acceptable values for normal milk. With the current standards for SCC of 1,000,000/ml as legal limit for abnormal milk control programs in goats, estrus synchronization programs and the estrus status should not be considered when bulk-tank milk SCC is being investigated.

Variations during lactation in total and differential leukocyte counts, N-acetyl-beta-D-glucosaminidase, antitrypsin and serum albumin in foremilk and residual milk from non-infected quarters in the bovine

Quarter samples of foremilk and residual milk were taken approximately every second week from 2 days post partum (pp) throughout lactation month 9, from 5 dairy cows in their second lactation period. Bacteriologically positive milk samples were excluded. The aim was to study the variation in total and differential leukocyte counts, N-acetyl-beta-D-glucosaminidase (NAGase), antitrypsin (ATR) and serum albumin (BSA) in milk during the lactation period and different stages of oestrous cycle. Also the between milkings variation was studied from lactation month 4 to 9. At 2 days pp, each fraction of milk contained significantly higher numbers of leukocytes and had a higher activity of NAGase and ATR than later in the lactation period. In foremilk the highest content of BSA was also recorded at 2 days pp. From lactation month 2 to 9, stage of lactation had, in general, a slight effect on the variation in the variables measured. The total leukocyte count in residual milk tended to increase as lactation proceeded. The proportion of monocyte-macrophages in foremilk was significantly decreased during the last 4 months. NAGase and BSA in both fractions and ATR in residual milk increased significantly towards the end of the lactation period. From lactation month 4 to 9 the highest recorded ranges of variation between milkings, within quarter and stage of lactation, in the total leukocyte count, proportions of neutrophils, lymphocytes, monocyte-macrophages, NAGase, ATR and BSA in foremilk were 215 x 10(3)/ml, 42%, 34%, 54%, 6.68 units, 0.36 units and 0.14 mg/ml respectively. The corresponding figures in residual milk were higher except for the variation in BSA which was slightly lower in residual milk than in foremilk. In residual milk there was a positive correlation between the proportion of neutrophils and the total leukocyte count, when calculated on data from all cows and the entire experimental period. During the oestrous periods, the proportion of neutrophils in residual milk was higher than during the dioestrous periods. Foremilk and residual milk differed in the total as well as the differential leukocyte counts in all the various stages of lactation, whereas the contents of NAGase, ATR and BSA were equal in both fractions. The exception was 2 days pp when the proportions of lymphocytes were equal in both fractions and BSA-significantly higher in foremilk than in residual milk.

Influence of exogenous estradiol on the concentration of antitrypsin, albumin, N-acetyl-beta-D-glucosaminidase and somatic cells in milk of cows at various lactation stages

Estradiol benzoate (0.02 mg/kg of body weight) was injected (i.m.) daily to 13 ovariectomized cows in their first or third lactations during early (60-90 days), mid (140-200 days) and late (240-300 days) lactation. The majority of the udder quarters were free of bacteria throughout the experiment. Signs of clinical mastitis were observed after 9-19 days of treatment in cows at mid and late lactation. This was accompanied by a decrease in milk yield, an increase in milk somatic cell count (MSCC) and increases in milk concentration of antitrypsin and serum albumin (as indicator of increased permeability); and milk NAGase activity (as indicator of epithelial cell damage or release of the enzyme from phagocytes). NAGase activity was first to increase and on some occasions was not accompanied by an increased MSCC. The response was either absent (first lactation) or relatively mild (third lactation) in cows at the early stages of lactation. The intensity of the inflammatory response increased with advancing lactation stage. Generally, the response of cows in the third lactation was greater than that of cows in the first lactation at a corresponding stage of lactation. Three cows which received the control treatment with vehicle alone showed no changes in any of the parameters except a slight decrease in antitrypsin. All inflammatory indicators correlated negatively with quarter milk production; milk NAGase activity was superior in this respect (r = -0.75). All correlation coefficients were generally higher after, rather than before the hormone treatment.