The aim of this study was to determine how evaporative cooling modifies body function with respect to water metabolism and other variables relevant to milk synthesis in crossbred cattle. The study was conducted on two groups of 0.875HF:0.125RS crossbred Holstein cattle (87.5%) housed in an open-sided barn with a tiled roof (non-cooled animals) and in a close-sided barn under an evaporative cooling system (cooled animals). The maximum ambient temperature and relative humidity for the non-cooled group were 33 degrees C and 61%, with the corresponding values for the evaporatively cooled barn being 28 degrees C and 84%, respectively. The temperature humidity index (THI) of under non-cooled conditions was higher (P < 0.05) than that in the cooled barn. Rectal temperatures and respiration rates of non-cooled animals were higher (P < 0.05) than those of cooled animals. Daily dry matter intake (DMI) of cooled animals was higher while water intakes were lower (P < 0.05) than those of non-cooled animals. The mean absolute values of plasma volume, blood volume, and extracellular fluid (ECF) of cooled animals were significantly higher (P < 0.05) than those of non-cooled animals throughout all stages of lactation. Milk yields of cooled animals were higher by 42%, 36% and 79% on average than those of non-cooled animals during early-, mid- and late-lactation, respectively. The decline in milk yields as lactation advances was markedly apparent in late-lactating non-cooled animals, while no significant changes in milk composition at different stages of lactation were observed in either group. Mean arterial plasma concentrations, arteriovenous concentration differences (A-V differences) and the extraction ratio across the mammary gland for acetate, glucose and triglyceride of cooled animals were not significantly different compared with values for non-cooled animals. No differences were seen in plasma hormonal levels for triiodotyronine (T(3)) and insulin-like growth factor-1 (IGF-1), but plasma cortisol and thyroxine (T(4)) levels tended to be lower in non-cooled animals. This study suggests that low cooling temperature accompanied by high humidity influences a galactopoietic effect, in part through increases in ECF, blood volume and plasma volume in association with an increase in DMI, which partitions the distribution of nutrients to the mammary gland for milk synthesis. Cooled animals were unable to maintain high milk yield as lactation advances even though a high level of body fluids was maintained during long-term cooled exposure. The decline in milk yield, coinciding with a decrease in net energy for lactation as lactation advances, could be attributed to a local change within the mammary gland.

ABSTRACT:Superovulation is an important step in assisted reproductive technology. Due to its short half-life, follicle stimulating hormone is usually given twice daily to ewes for three to five days, which is both time-and labour-intensive. However, dissolving follicle stimulating hormone in degradable polymers to delay absorbtion has been effective in ruminants. Experiment 1 was performed to compare a split-single follicle stimulating hormone dissolved in hyaluronan (S group; 150 mg follicle stimulating hormone on the first day and 30 mg 48 h later; n = 21) and six decreasing doses of follicle stimulating hormone (M group; 50, 50, 30, 30, 10 and 10 mg; n = 22) at 12-h intervals. Ovarian responses and numbers of recovered ova/embryos did not differ significantly between groups. However, there tended to be more Grade 1 and 2 embryos in S vs M groups (mean ± SEM, 5.1 ± 4.9 vs 2.9 ± 2.9, respectively; P = 0.08). Experiment 2 tested the effectiveness of a simplified split-single follicle stimulating hormone in purebred sheep on a commercial farm. The numbers of recovered good-grade embryos (day 2) were 4.8 ± 5.0 and 4.0 ± 2.5 per donors in Corriedale and Bond sheep breeds, respectively. We conclude that this modified technique for ewe superovulation improved animal welfare, reduced animal handling and labour and yielded results similar to or better than conventional twice-daily follicle stimulating hormone treatments.

The effects of utilizing evaporative cooling system equipped with tunnel ventilation on postpartum ovarian activities, energy balance and milk production of early lactating dairy cows under hot and humid climates were studied from parturition to 22 wk postpartum. Thirty-four crossbred Holstein-Friesian (93.75% HF×6.25% Bos indicus) primiparous cows were randomly assigned to one of two groups. Cooled cows (n = 17; treatment) were housed in the tunnel ventilated barn equipped with evaporative cooling system and uncooled (n = 17; control) were housed in the naturally ventilated barn without supplemental cooling system. Cooled cows had greater (p<0.05) dry matter intake and milk production than uncooled cows. Days to the energy balance (EB) nadir did not differ between groups. However, days to equilibrium EB for uncooled cows was longer (p<0.05) than for cooled cows. There was no significant difference in postpartum anovular condition between cooled and uncooled cows. The interval from parturition to first postpartum ovulation did not differ between groups (31.4±4.3 and 26.1±3.6 day, respectively). These results suggest that the evaporative cooling and tunnel ventilation has the potential to decrease the severity of heat stress and improve both milk production and metabolic efficiency during early lactation without affecting reproductive function in dairy cows under hot and humid climates.

ABSTRACT. The objective of the experiment was to improve the multifollicle stimulation technique and the ovarian response examination in prepubertal swamp buffalo calves. Six animals were stimulated by gonadotropin hormone 7 days after a progesterone ear-implant. The first stimulation was done by giving 24 mg FSH + 100 µg GnRH (FSH+GnRH) and the second, one month after by giving 2,000 IU PMSG + 100 µg GnRH (PMSG+GnRH). Twenty-four hours after GnRH, the ovarian responses were checked using rectal palpation and real-time B mode ultrasonography. Five out of six animals (83.3%) responsed to both treatments and were selected for oocyte collection. The oocytes were aspirated directly following a caudal midline laparotomy. The results of ovarian responses to FSH+GnRH and PMSG+GnRH averaged 17.6 ± 12.1 (L=9.8 ± 8.7, R=7.8 ± 6.2) and 17.4 ± 5.6 (L=9.4 ± 2.9, R=8.0 ± 3.7), respectively. The average number of recovered oocytes per animal was 9.0 ± 6.4 and 8.4 ± 1.1, respectively which represented a recovery rate of 56.3 (± 9.2)% and 51.9 (± 10.3)%. More than eighty percent of the recovered oocytes were in an immature stage with more than 2-3 layers of compact cumulus mass. The present study showed that the oocytes were collected successfully in prepubetal buffalo calves after the FSH+GnRH or PMSG+GnRH stimulation and most of the recovered oocytes were immature, which made them suitable for in vitro maturation and fertilization. first stimulation by giving a single injection of PMSG. Seventy-two hours after the injection of PMSG, 100 µg of GnRH was given. The protocol of hormonal treatment, modified from Techakumphu et al. [12], is shown in Table 1. Determination of ovarian responses:The ovarian responses (size, number of follicles and corpora hemorrhagica) were examined 24 hr after GnRH administration by rectal palpation and the real-time B mode ultrasonography d using a 5.5 MHz transducer designed for transvaginal examination. Frozen real-time ultrasonographs were recorded on a black and white printer.Only calves with more than two follicles in each ovary were classified as positive responses and were selected for oocytes collection by laparotomy under general anesthesia. The calves were tranquilized with Xylazine hydrochloride e (10 mg/10 kg body weight I/M) and 15 min later a single dose of 20% thiopentone (7 mg/kg) was injected intravenously for immobilization. The animals were intubulated immediately and general anesthesia was maintained by an intravenous drip of 1% thiopentone in 0.9% normal saline. An abdominal midline incision was performed between the udder teats. The cervix, uterine horn and ovaries were examined through the incision site. The size and number of follicles and corpora hemorrhagica

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