Carbonic anhydrase and its isozymes in heat stressed white Leghorn hens.

Experiments were conducted to study the effect of heat stress on uterine tissue carbonic anhydrase levels and their isozyme patterns in relation to production of no- and thin-shelled eggs. Birds exposed to naturally occurring heat stress had lower enzyme levels in their uteri than birds kept in an air-conditioned pen. 4 isozyme bands of carbonic anhydrase were visible in uterine tissue homogenate from both groups of birds. Isozymes were suppressed in heat-stressed birds, as was evident from staining intensities of the bands. This provided evidence to the effect that heat stress not only decreased the total quantity of carbonic anhydrase in the uteri of the hens but also suppressed its isozyme fractions, leading to greater production of no-shell and thin-shelled eggs.

Thyroid function in relation to reproductive efficiency in postpartum buffaloes (Bubalus bubalis) during summer and winter.

Thyroid function was studied by estimating of plasma-protein-bound iodine (PBI), in buffaloes, from 0 to 57 days postpartum. PBI values (microgram/100 ml) were lowest on day 1 postpartum, followed by a gradual increase by day 57. The values were consistently lower (P less than 0.01) during summer (3.79 +/- 0.13 micrograms/100 ml), as compared to winter (5.06 +/- 0.27). A lower value (P less than 0.01) was obtained in animals requiring less than 30 days (3.53 +/- 0.45) or more than 30 days (4.88 +/- 0.27) for uterine involution. The values were 4.56 +/- 0.13, 5.03 +/- 0.68 and 2.72 +/- 0.50 in animals requiring less than 25, 25-50 and more than 50 days for initiation of follicular development (P less than 0.01). Similarly the values were 4.95 +/- 0.38, 3.95 +/- 0.45 and 4.03 +/- 0.59 in buffaloes having postpartum oestrus intervals less than 45, 45-90, and more than 90 days (P less than 0.01). Higher values (P less than 0.05) were obtained in conceiving (4.55 +/- 0.41), as compared to non-conceiving animals (4.21 +/- 0.31). It can be concluded that the thyroid function is depressed during summer and in poorly reproducing buffaloes.

Seasonal variations in plasma hormones and reproductive efficiency in early postpartum buffalo.

Investigations were carried out on twenty newly calved Murrah buffalo that were divided into two sets of ten each during winter (December to February) and summer (May to September). Recommended feeding and management practices were followed. Blood samples were collected on Days 0, 1, 2, 4, 6, 8, 15, 22, 29, 36, 43, 50 and 57 postpartum for hormone radioimmune assay (RIA). The values of reproductive parameters and hormone levels during winter and summer, respectively, were the following for uterine involution, 39.50 +/- 2.74 d and 32.50 +/- 3.01 d; first postpartum estrus interval, 70.10 +/- 9.62 d and 37.40 +/- 11.82 d; number of services per conception, 1.57 +/- 0.29 and 2.40 +/- 0.68; first service conception rate, 40 and 20 %, overall conception rate, 70 and 40 %; 13,14-Dihydro-15-keto prostaglandin F(2alpha) (PGFM), 1.78 +/- 0.26 ng/ml and 2.62 +/- 0.30 ng/ml; progesterone, 1.09 +/- 0.14 ng/ml and 0.65 +/- 0.77 ng/ml. A negative correlation (r = -0.83, P 0.05 ) was observed between PGFM and progesterone. Although, summer stress hastens uterine involution and first postpartum estrus interval, overall reproductive efficiency is impaired due to deficiency of progesterone, which is essential for embryo survival.

Activity and distribution of carbonic anhydrase in the oviduct of the laying hen (Gallus domesticus) during egg formation at three different periods in spring and summer seasons.

Investigations were undertaken to study the possible role of oviducal carbonic anhydrase during egg shell formation in 108 layers of Babcock-300 strain of three age groups of 21-24, 32-36 and 68-72 week old during spring and summer. Eighteen layers of each age group were subgrouped in three cyclic positions just after oviposition, 4 and 18 hours after oviposition. The distribution of carbonic anhydrase was significantly (P less than 0.01) higher in shell gland and low in isthmus in all the three age groups during both seasons. Carbonic anhydrase decreased (P less than 0.01) in summer in all three age groups. It was significantly (P less than 0.01) higher in magnum at the 14th h after oviposition in all the three age groups in both seasons, which established a new pattern of activity. Decreased concentration of the enzyme during the thermal stress period might be one of the factors responsible for the thinness of egg shell and for the increase in the number of soft shelled eggs.

Effect of environmental cooling on certain biochemical responses in broilers.

Investigations were undertaken to study the effect of different thermal environments of growth attributes of broilers. One hundred fifty-day old chicks of both sexes were kept each in control, foggers, exhaust fan and cooler groups during hot and dry, and hot and humid periods to assess the effect of cooling on growth efficiency of broilers in terms of blood cholesterol and ascorbic acid. The average cholesterol content (mg/100 ml) of blood plasma was highest in the control groups of both the periods. The birds of the control and exhaust groups were more stressed as compared to birds in fogger and cooler groups where the cholesterol content was least. The average values for the ascorbic acid content of blood plasma (mg/100 ml) were highest in the cooler groups of both the periods showing the greater resistance of these birds against the thermal stress. The increased amounts of ascorbic acid in the cooler groups were positively correlated to the heavier body weights of the birds in this particular group. In contrast, the birds in the control and exhaust groups had minimum amounts of ascorbic acid content at all ages irrespective of sexes. Therefore, from the above results of cholesterol content and ascorbic acid concentration, it is concluded that hot and humid period at Ludhiana is the most stressful and evaporative cooling is the most efficient method for alleviating summer stress in broilers.

Effect of spray and evaporative cooling on certain galactopoietic responses in buffaloes (Bubalus bubalis).

Nine normal lactating Murrah buffaloes from Punjab Agricultural University Dairy herd were used to assess the effect of spray and evaporative cooling on certain galactopoietic responses in buffaloes in three equal groups of control (Group I), showers (Group II) and evaporative cooling (Group III). At 10.30, 12.30, 14.30 and 16.30 h daily the animals in Group II were given showers for fifteen minutes while the animals of Group III were kept on evaporative cooling system from 07.00 to 21.00 h daily. All the animals of Groups I, II and III were given showers by splashing water on their bodies with buckets once a day as a general routine being practised in the farm. Physical parameters included were dry bulb temperature, wet bulb temperature, maximum and minimum temperature, light intensity, % R. H., total day length and cooling power of air. The various galactopoietic responses recorded were the let down time, the milking time, the milk yield, the average flow rate, the fat and lactose percentages. The results of this study revealed that the showers amd the evaporative cooling were responsible for increasing the galactopoietic responses, i. e. the milk yield, the milking time, the the average flow rate and decreasing the let down time in both the periods. This may be attributed to the added comfort to such animals.