Katsuya Kida

Peripheral administration of kisspeptin-10 increases plasma concentrations of GH as well as LH in prepubertal Holstein heifers

This study was conducted to estimate the effects of kisspeptin-10 on blood concentrations of LH and GH in prepubertal dairy heifers. Heifers received a single injection of 1 mg kisspeptin-10 (n=5) or saline (n=5) intravenously, and serial blood samples were collected at 15-min intervals to analyze the response curves of both LH and GH after injection. Peak-shaped responses were observed for concentrations of LH and GH, and the peaks were observed at 27+/-3 and 75+/-9 min, respectively, after injection, only in heifers injected with kisspeptin-10. These data suggest various possible important links among kisspeptin, the reproductive axis, and also the somatotropic axis in prepubertal Holstein heifers.

Effect of local neutralization of basic fibroblast growth factor or vascular endothelial growth factor by a specific antibody on the development of the corpus luteum in the cow

Active angiogenesis and progesterone (P) synthesis occur in parallel during development of the corpus luteum (CL). Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) are known to stimulate angiogenesis and P synthesis in vitro. The aim of the present study was to investigate the impact of bFGF or VEGF on the CL development in the cow by using a specific antibody against bFGF or VEGF. bFGF antibody, VEGF antibody, or saline as a control (n = 4 cows/treatment) were injected directly into the CL immediately after ovulation (Day 1), and the treatment was continued for 3 times/day over 7 days. Luteal biopsies were applied on Day 8 of the estrous cycle to determine the expression of genes associated with P synthesis and angiogenesis. Intraluteal injections with the bFGF antibody or the VEGF antibody markedly decreased the CL volume, plasma P concentration and StAR mRNA expression. bFGF antibody treatment decreased the mRNA expression of bFGF, FGF receptor‐1, VEGF120, and angiopoietin (ANPT)‐1, and increased ANPT‐2/ANPT‐1 ratio. However, VEGF antibody treatment decreased ANPT‐2 mRNA expression and ANPT‐2/ANPT‐1 ratio. These results indicate that local neutralization of bFGF or VEGF changes genes regulating angiogenesis and P synthesis, and remarkably suppresses the CL size and P secretion during the development of CL in the cow, supporting the concept that bFGF and VEGF control the CL formation and function. Mol. Reprod. Dev. 75: 1449–1456, 2008.

Effect of β-carotene supply during close-up dry period on the onset of first postpartum luteal activity in dairy cows.

The aim of this study was to examine the effect of β-carotene supply during the close-up dry period on the onset of first postpartum luteal activity in dairy cows. Twelve cows were supplied with 2000 mg of β-carotene (20 g Rovimix(®) β-Carotene containing 10% β-carotene; DSM Nutrition Japan K.K., Tokyo, Japan) by oral administration daily from day 21 before expected calving date to parturition. Fourteen cows (control) did not receive β-carotene supplementation. Blood samples were obtained on days 21, 14 and 7 before expected calving date and on days 1, 7, 14, 21 postpartum. When the plasma progesterone concentration exceeded 1 ng/ml by day 21 postpartum, luteal activity was assumed to have been initiated. The result showed that serum β-carotene concentrations in the β-carotene cows were higher than in the control cows during the experimental period (p < 0.01). The number of cows with the onset of luteal activity by day 21 postpartum was 9/12 in the β-carotene cows and 4/14 in the control cows (p < 0.05). Retinol, certain metabolic parameters and metabolic hormones concentrations did not differ between β-carotene and control cows. In addition, serum retinol concentration in β-carotene cows without luteal activity was lower than in β-carotene cows with luteal activity (p < 0.05), and serum gamma-glutamyl transpeptidase concentration in β-carotene cows with luteal activity (p < 0.05) and control cows without luteal activity (p < 0.01) was higher than in control cows with luteal activity. In conclusion, β-carotene supply during the close-up dry period may support the onset of luteal activity during early lactation in dairy cows.

The effect of temperature on survival of pathogenic bacteria in biogas plants

The paper deals with the hygienic advantages of sanitation to treat dairy manure in full-scale biogas plants. The slurry samples were collected from two thermophilic biogas plants (55°C) and two mesophilic biogas plants (38°C) in Hokkaido Japan. A detectable number of Coli-aerogenes group and Enterococcus in the slurries after anaerobic digestion (AD) could not be found in either thermophilic biogas plants. However, in both mesophilic biogas plants the viable numbers of Coli-aerogenes group and Enterococcus were detected in the slurries even after anaerobic digestion. The mean decimation reduction time (T(90) ) values of the Coli-aerogenes group and Enterococcus in the slurries during mesophilic digestion were 13.3 days and 16.7 days, respectively.

Generation of IFN-γ-producing cells that recognize the major piroplasm surface protein in Theileria orientalis-infected bovines.

Theileriosis is a tick-borne protozoan disease caused by Theileria species. The Theileria species are classified into two groups depending on the cell type in which they proliferate and the clinical symptoms. The first group consists of lymphoproliferative Theileria species (T. parva and T. annulata), which mainly proliferate in lymphocytes, causing uncontrolled lymphocyte proliferation. The other group consists of a nonlymphoproliferative Theileria species (T. orientalis, also known as T. sergenti) that proliferates in erythrocytes and causes hemolytic anemia. Based on reports of generation of antigen-specific CD4(+) and CD8(+) T cells in lymphoproliferative theileriosis, we investigated whether T cells specific to the T. orientalis antigen are present in the nonlymphoproliferative form of the disease. In this study, we developed a new assay based on an enzyme-linked immunospot (ELISpot) to detect interferon-gamma (IFN-gamma)- and interleukin-10 (IL-10)-secreting cells in a series of cryogenically preserved bovine peripheral blood mononuclear cells (PBMCs). We first determined that IFN-gamma- and IL-10-secreting T cells were present in PBMCs by stimulating them with phytohemagglutinin L (PHA-L=red kidney bean lectin L, known as T cell stimulator), and then determined whether T. orientalis-specific T cells are present in T. orientalis-infected bovines. Peptides derived from T. orientalis major piroplasm surface protein (MPSP) were used as a T. orientalis-specific stimulator in the ELISpot assay, and peptides from glycoprotein B (gB) of the bovine herpes virus-1 (BHV-1) were used as a BHV-1-specific stimulator as a control for monitoring the immune response. Compared with results obtained using the BHV-1 (gB peptides)-specific IFN-gamma ELISpot assay to assess BHV-1-immunized Holsteins, prominent T. orientalis MPSP peptide-specific IFN-gamma and IL-10 positive spots were detected in T. orientalis-infected Holsteins but weak positive responses were exhibited by T. orientalis-infected Angus and Japanese Black cattle. As far as we are aware, this is the first report to show direct evidence of the presence of T. orientalis-specific T cells in T. orientalis-infected bovines using an antigen-specific ELISpot assay system and that T. orientalis-specific, IFN-gamma- and IL-10-producing T cells are produced in T. orientalis-infected Holsteins.

Tissue Distribution of Neospora caninum in Experimentally Infected Cattle

ABSTRACT Histopathology and quantitative PCR (qPCR) were used to determine the tissue distribution of Neospora caninum in calves at 80 days postinfection. Our findings revealed that the most appropriate brain areas for researching N. caninum pathogenesis were the amygdala and hippocampus for qPCR and the corpus striatum and diencephalon for histopathology.

Effects of exogenous oxytocin on uterine blood flow in puerperal dairy cows: the impact of days after parturition and retained fetal membranes.

The objective of this study was to examine whether an oxytocin challenge test (OCT), evaluated by measuring the changes in uterine blood flow using transrectal colour Doppler ultrasonography, is a suitable non-invasive method to determine uterine contractility in puerperal dairy cows. The changes in uterine blood flow during uterine contractions induced by oxytocin were evaluated on days 2 and 5 postpartum (pp). Twelve clinically healthy Holstein cows were randomly assigned into two groups: (1) oxytocin group (n=7), 50 IU oxytocin injected IM and (2) control group (n=5), 5 mL saline injected IM. Blood flow volume (BFV) and pulsatility index (PI) in the uterine arteries were determined before and after injection for 120 min on days 2 and 5 pp. BFV declined and PI increased rapidly after oxytocin injection on day 2 (P<0.05), whereas oxytocin on day 5 pp did not cause changes in blood flow parameters. The result confirmed that uterine responsiveness to oxytocin decreases with time postpartum in healthy cows. The same OCT was applied in cows with retained fetal membranes (n=6) on day 2 pp, however uterine blood flow showed no change after oxytocin injection. The results showed that an OCT on day 2 pp may be a useful method for investigating the uterine contractile response to oxytocin (reflected as the decrease of uterine blood flow) and the potential pathophysiology of uterine involution in cows.

The absence of corpus luteum formation alters the endocrine profile and affects follicular development during the first follicular wave in cattle

We previously established a bovine experimental model showing that the corpus luteum (CL) does not appear following aspiration of the preovulatory follicle before the onset of LH surge. Using this model, the present study aimed to determine the profile of follicular development and the endocrinological environment in the absence of CL with variable nadir circulating progesterone (P(4)) concentrations during the oestrous cycle in cattle. Luteolysis was induced in heifers and cows and they were assigned either to have the dominant follicle aspirated (CL-absent) or ovulation induced (CL-present). Ultrasound scanning to observe the diameter of each follicle and blood collection was performed from the day of follicular aspiration or ovulation and continued for 6 days. The CL-absent cattle maintained nadir circulating P(4) throughout the experimental period and showed a similar diameter between the largest and second largest follicle, resulting in co-dominant follicles. Oestradiol (E(2)) concentrations were greater in the CL-absent cows than in the CL-present cows at day -1, day 1 and day 2 from follicular deviation. The CL-absent cows had a higher basal concentration, area under the curve (AUC), pulse amplitude and pulse frequency of LH than the CL-present cows. After follicular deviation, the CL-absent cows showed a greater basal concentration, AUC and pulse amplitude of growth hormone (GH) than the CL-present cows. These results suggest that the absence of CL accompanying nadir circulating P(4) induces an enhancement of LH pulses, which involves the growth of the co-dominant follicles. Our results also suggest that circulating levels of P(4) and E(2) affect pulsatile GH secretion in cattle.

Ovarian stimulation with follicle-stimulating hormone under increasing or minimal concentration of progesterone in dairy cows

The objective of this study was to investigate the effect of the presence or absence of Corpus luteum (CL) on the follicular population during superstimulation in dairy cows (Holstein-Friesian cattle). Animals were divided into two groups as follows: (1) Growing CL group (G1): Cows (n=7) received a total dose of 28 Armour units (AU) follicle-stimulating hormone (FSH) through the first 4 d (twice daily) after spontaneous ovulation (Day 0). (2) CL Absence group (G2): Cows (n=10) received prostaglandin F(2alpha) (PGF(2alpha)) at 9 or 10 d after ovulation. After 36h, all the follicles (larger than 5mm) were aspirated (Day 0). The FSH treatment started 24h after aspiration and continued for 4 d. The number of small (3 to <5mm), medium (5 to <8mm), and large (> or = 8mm) follicles was examined on Days 1, 3, and 5 in all groups. Blood samples were collected daily for 5 d, and progesterone (P(4)), estradiol (E(2)), insulin-like growth factor-1 (IGF-1), and growth hormone (GH) in plasma were measured by enzyme immunoassays. The results showed that in G1, the P(4) level increased gradually from 0.5 ng/mL at Day 1 to 2 ng/mL at Day 5, whereas in G2, the P(4) level was completely below 0.5 ng/mL. All cows of the G2 group showed an increase of E(2) at Day 3 or Day 4 followed by an increase of IGF-1 within 24h, while GH increased concomitantly with the E(2) increase in 8 of 10 trials. On the other hand, cows of the G1 group showed neither E(2) nor IGF-1 increase. Moreover, at the end of the treatment, the number of follicles in the G2 group was significantly increased compared with that of the G1 group (22.8+/-2.0 vs. 11.6+/-2.0). In conclusion, low P(4) level during FSH treatment enhanced multiple follicular growth and E(2) secretion, which was followed by increase of IGF-1 and GH. Therefore, the absence of the CL may play a critical role in the superovulation response by controlling the number of growing follicles.

Relationship between the degree of insulin resistance during late gestation and postpartum performance in dairy cows and factors that affect growth and metabolic status of their calves

This study aimed to investigate the effects of insulin resistance (IR) during the close-up dry period on the metabolic status and performance of dairy cows as well as to determine the effects on body weight (BW) and metabolic status of their calves. An insulin tolerance test (ITT) was conducted by administering 0.05 IU/kg BW of insulin to 34 multiparous Holstein cows at 3 weeks prepartum. Blood samples were collected at 0, 30, 45 and 60 min after insulin injection, and cows were divided into two groups based on the time required for glucose to reach the minimum levels [non-IR (NIR), 45 min (n=28); and IR, 60 min (n=6)]. Blood or milk sampling and body condition score (BCS) estimation were performed twice weekly during the experimental period. Blood samples from calves were collected immediately after birth. Cows with IR showed lower BCS (P<0.05) and serum urea nitrogen (P<0.05) and glucose concentration (P=0.05) before calving, and lower serum non-esterified fatty acid concentration (P<0.05) and milk yield (P<0.05) and earlier resumption of luteal activity (P<0.05) after calving; their calves showed lower BW (P<0.05) and plasma insulin-like growth factor-I concentration (P<0.001) and higher plasma insulin concentration (P<0.05). In conclusion, IR at 3 weeks prepartum in dairy cows is related to postpartum metabolic status and performance along with growth and metabolic status of their calves.