Effect of harvesting strategy of second-cut orchardgrass silage on feed intake, digestion, and milk production in dairy cows.

We investigated the effects of regrowth interval and first-cut timing on the dietary characteristics of second-cut orchardgrass silage and feed intake and milk production in dairy cows fed second-cut orchardgrass silage. The second-cut grasses were harvested 7w after the first-cut at the early stage (E7w) or at the heading stage (H7w), or harvested 6w after the first-cut at the early stage (E6w) from orchardgrass sward, and then ensiled. We evaluated the effect of regrowth interval by comparing E7w and E6w, and the effect of first-cut timing by comparing E7w and H7w. Six multiparous Holstein cows were used in a replicated 3 × 3 Latin square design, with three dietary treatments: diets containing E7w, E6w, or H7w silage at 30% dietary dry matter. We observed that feeding E6w silage instead of E7w silage increased fiber digestibility, dry matter intake, and milk production; however, the first-cut timing (E7w vs. H7w) did not affect nutrient content and digestibility, feed intake, or lactation performance. These results show that harvesting at short regrowth intervals for second-cut orchardgrass can be an effective strategy for improving feed utilization and milk yield; however, the first-cut timing for second-cut orchardgrass has little impact.

Effects of ear corn silage supplementation on milk production and milk fatty acid profiles in grazing dairy farms.

This study investigated the effects of substituting ear corn silage (ECS) for commercial formula feed on milk production and milk fatty acid profiles in grazing dairy farms during the summer season. A field survey was conducted on five grazing dairy farms in every summer month of 2017, 2018, and 2019. Three of the five farms substituted fresh ECS for the commercial formula feed at a ratio of 2:1 from July of each year (ECS farms). Other farms maintained the same feeding management as before (non-ECS farms). An interview survey was conducted on each farm to calculate feed intake and milk yield per cow. Feed and milk samples were collected in each survey. Milk compositions and milk fatty acid profiles were determined. The substitution of ECS for the commercial formula feed did not affect milk yield or milk composition, but ECS farms maintained low levels of milk urea compared with non-ECS farms (p < .01). The ECS substitution also influenced some of the milk fatty acid proportions; C16:0 and C16:1 increased, and trans-11 C18:1, cis-9,trans-11 C18:2, and the sum of polyunsaturated fatty acids decreased, while these fatty acid proportions were maintained in non-ECS farms throughout the summer season (p < .05).

Effect of time at pasture and herbage intake on profile of volatile organic compounds of dairy cow milk.

Volatile organic compounds (VOCs) in milk were investigated as quantitative markers of herbage intake (HI) at pasture. Eight Holstein cows were fed indoors with concentrate and conserved forages (grass silage, corn silage and hay) (NG), then were divided into three treatments according to the duration of access to pasture: 4 h (G4), 8 h (G8), and 20 h (G20) per day. The HIs were 4.3, 8.6, and 13.0 kg dry matter/day for the G4, G8 and G20 treatments, respectively. Milk from cows was sampled and analyzed VOCs by the steam distillation-extraction method and gas chromatography-mass spectrometry (GC-MS). From the intensity of the GC peak area, the levels of 1-phytene (3,7,11,15-tetramethyl-1-hexadecene) and 2-phytene (3,7,11,15-tetramethyl-2-hexadecene) were lowest in NG treatment and markedly increased with grazing time at pasture. With simple regression analysis on the HI to each diterpenoid, a strong correlation was found between the intensity of 1-phytene in the milk and the HI (r = 0.807, P < 0.001). 1-phytene content in milk could be useful as a quantitative marker of the HI of grazing cows.

Radiation-associated changes in the length of telomeres in peripheral leukocytes from inpatients with cancer.

PURPOSE: The telomere length of somatic cells shortens with age and with other endogenous and exogenous pathogenic factors. However, the effects of radiation therapy on telomere DNA of non-cancer tissue have not been thoroughly investigated. This study analyzed the telomere length of inpatients with cancer treated with radiation therapy to see whether the telomere lengths change in response to therapeutic radiation. MATERIALS AND METHODS: Twenty-five patients were enrolled in the study. The patients had lung cancer, prostate cancer, thyroid cancer, hepatoma, or rectal cancer. They received radiation therapy with a dose range of 15-74 Gy. The telomere lengths and telomere length distribution in peripheral leukocytes were analyzed by using a Southern blot-based method. RESULTS: The telomere length and the telomere length distribution of the peripheral leukocytes did not change after radiation therapy. However, there was a significant proportional decrease in the short telomere fraction (< 4.4 kb) per day and per Gy. CONCLUSIONS: This observation suggested that the telomere length distribution of peripheral leukocytes could be affected by radiation therapy, and that the effect of radiation tends to appear in cells with short telomeres. Radiation therapy-associated somatic telomere length change within a short range of time, about three months or shorter, can be detected by analyzing the mean telomere length and telomere length distribution.

Detection of a novel bovine papillomavirus type 11 (BPV-11) using xipapillomavirus consensus polymerase chain reaction primers.

Polymerase chain reaction-based bovine papillomavirus (BPV) detection methods using a combination of two primer sets, subAup/subAdw and subBup/subBdw, have enabled the broad-spectrum detection of most characterized BPV types. These methods were used to detect the partial L1 nucleotide sequence of BPV types from 167 cutaneous warts in cattle. Three potentially new viruses were detected using subBup/subBdw primer sets. The partial nucleotide sequences of these viruses were most similar to BPV-4, -6 and -9. Whole genome sequencing of one sample defines a new BPV type in the genus Xipapillomavirus, designated BPV-11.

Transient receptor potential (TRP) protein 7 acts as a G protein-activated Ca2+ channel mediating angiotensin II-induced myocardial apoptosis.

Transient receptor potential (TRP) proteins have been identified as cation channels that are activated by agonist-receptor coupling and mediate various cellular functions. TRPC7, a homologue of TRP channels, has been shown to act as a Ca2+ channel activated by G protein-coupled stimulation and to be abundantly expressed in the heart with an as-yet-unknown function. We studied the role of TRPC7 in G protein-activated signaling in HEK293 cells and cultured cardiomyocytes in vitro transfected with FLAG-tagged TRPC7 cDNA and in Dahl salt-sensitive rats with heart failure in vivo. TRPC7-transfected HEK293 cells showed an augmentation of carbachol-induced intracellular Ca2+ transient, which was attenuated under a Ca2+-free condition or in the presence of SK&F96365 (a Ca2+-permeable channel blocker). Upon stimulation with angiotensin II (Ang II), cultured neonatal rat cardiomyocytes transfected with TRPC7 exhibited a significant increase in apoptosis detected by TUNEL staining, accompanied with a decrease in the expression of atrial natriuretic factor and destruction of actin fibers, as compared with non-transfected cardiomyocytes. Ang II-induced apoptosis was inhibited by CV-11974 (Candesartan; Ang II type 1 [AT1] receptor blocker), SK&F96365, and FK506 (calcineurin inhibitor). In Dahl salt-sensitive rats, apoptosis and TRPC7 expression were increased in the failing myocardium, and a long-term treatment with temocapril, an angiotensin-converting enzyme inhibitor, suppressed both. Our findings suggest that TRPC7 could act as a Ca2+ channel activated by AT1 receptors, leading to myocardial apoptosis possibly via a calcineurin-dependent pathway. TRPC7 might be a key initiator linking AT1-activation to myocardial apoptosis, and thereby contributing to the process of heart failure.

Biochemical and transcriptomic analyses of two bovine skeletal muscles in Charolais bulls divergently selected for muscle growth.

This work aimed to investigate the consequences of muscle growth selection on muscle characteristics. An oxidative muscle (Rectus abdominis, RA) and a glycolytic one (Semitendinosus, ST) were studied in two groups of six extreme young Charolais bulls of high or low muscle growth. Mitochondrial activity was lower in muscles of bulls with high muscle growth. Transcriptomic studies allowed the identification of putatively differentially expressed genes. The differential expression between genetic types of two genes in RA (a heat shock protein and a thyroid receptor interacting protein) and of seven genes in ST (including LEU5, tropomyosin 2, and sarcosin) was confirmed by different statistical approaches or Northern blot analysis, as well as the differential expression of five genes (including PSMD4 and DPM synthase) between RA and ST. Both biochemical and transcriptomic results indicate that selection on muscle growth potential is associated with reduced slow-oxidative muscle characteristics. Further studies are required to understand the physiological importance of genes whose expression is changed by selection.

Beneficial effects of angiotensin-converting enzyme inhibition on sarcoplasmic reticulum function in the failing heart of the Dahl rat.

Inhibition of angiotensin-converting enzyme (ACE) retards the process of myocardial remodeling and contractile dysfunction that leads to heart failure. However, the intracellular mechanisms by which ACE inhibition preserves myocardial contractility are largely unclear. Using a model of heart failure induced by hypertension in Dahl salt-sensitive (DS) rats, the mechanisms by which ACE inhibitors (ACEI) exert a beneficial effect on myocardial contractility were studied. Dahl salt-resistant (DR) rats, DS rats not given temocapril (DS/T-), and DS rats treated with temocapril (10 mg/kg per day from 10 to 17 weeks of age, DS/T+) were fed an 8% NaCl diet from 8 to 17 weeks of age (n=8, each group). Echocardiography, hemodynamic measurement, histology, contraction of isolated skinned papillary muscle, and Western blot analysis were carried out. At an elevated final blood pressure similar to that of the DS/T- rats, DS/T+ rats exhibited (1) a decrease in left ventricular (LV) mass associated with decreases in both cardiomyocyte size and interstitial fibrosis; (2) improvement of both systolic and diastolic LV function; and (3) an increase in caffeine contraction after constant Ca(2+)-loading with 8-bromo-cAMP into the sarcoplasmic reticulum (SR) associated with an increase in Ser16-phosphorylated phospholamban, as compared with the DS/T- rats. In addition to inhibition of myocardial remodeling, a restoration of the Ca(2+)-handling ability of the SR by normalized phosphorylated phospholamban may contribute to the improved LV contractile function achieved by chronic treatment with an ACEI.

Chronic inhibition of Rho kinase blunts the process of left ventricular hypertrophy leading to cardiac contractile dysfunction in hypertension-induced heart failure.

The Gq-RhoA-Rho kinase pathway, activated by neurohormonal factors such as angiotensin II (Ang II), has been proposed to be one of the important signaling pathways involved in the progression of left ventricular (LV) hypertrophy to heart failure. We tested the hypothesis that chronic inhibition of Rho kinase prevents this process. Heart failure was induced in Dahl salt-sensitive (DS) rats fed an 8% NaCl diet from 8 until 17 weeks of age. Y-27632 (5 mg/kg per day), a selective Rho kinase inhibitor, was applied orally to DS rats starting at 10 weeks of age for 7 weeks (DS/Y+). DS rats without Y-27632 (DS/Y-) and Dahl salt-resistant (DR) rats fed the 8% NaCl diet were regarded as non-therapeutic and normotensive controls, respectively. At 17 weeks of age, there was no significant difference in the blood pressure of DS/Y- and DS/Y+ rats. DS/Y- rats exhibited: (1) increases in LV mass, cross-sectional area (CSA) of cardiomyocytes, and interstitial fibrosis; (2) contractile dysfunction, i.e. decreases in LV ejection fraction and % fractional shortening, and prolongation of time to peak tension as well as to 50% relaxation in the twitch contraction of isolated papillary muscle; and (3) increases in the protein expression of Galphaq and Rho kinase in the myocardial membrane fraction. In DS/Y+ rats, the degree of myocardial hypertrophy was significantly inhibited in association with improved contractile function, without a decrease in the degree of interstitial fibrosis. Our results suggest the possibility that the Gq-Rho kinase pathway plays an important role in the process of hypertension-induced LV hypertrophy leading to contractile dysfunction.

Breed differences in growth hormone and insulin secretion between lactating Japanese Black cows (beef type) and Holstein cows (dairy type).

This study was performed to clarify the levels of growth hormone (GH) and insulin (INS) secretions and the glucose response to INS during lactation in a representative beef breed in Japan, Japanese Black cows, and to compare them with their counterparts in a dairy breed, Holstein cows. Six Japanese Black and seven Holstein primiparous cows received a single intravenous injection of GH-releasing factor (GRF; 0.25 microg/kg), glucose (112.5 mg/kg), or INS (0.2 U/kg) from late pregnancy (2 weeks antepartum) to mid-lactation (6 months postpartum). Japanese Black cows had one-tenth of the total milk yield of Holstein cows during lactation, and significantly lower GRF-induced GH and higher glucose-induced INS secretions than Holstein cows at all stages. In Japanese Black cows, even with lactation, these secretions remained essentially unchanged, whilst Holstein cows showed higher GH and lower INS secretions after the onset of lactation as compared with cows in late pregnancy. Both breeds had similar glucose response to INS at the respective stages. These results suggest that, during lactation, Japanese Black cows may minimize the catabolic effects of GH and sustain the anabolic effects of INS, in contrast with Holstein cows, but have similar ability to inhibit INS-mediated glucose utilization in peripheral tissues to Holstein cows.

Effects of calmodulin and okadaic acid on myofibrillar Ca2+ sensitivity in cardiac myocytes.

Whereas it has been established that the phosphorylation of 20 kD regulatory myosin light chain (MLC20) is a key regulator of contraction in smooth muscle, troponin complex has been thought to be that of myofibrillar Ca2+ sensitivity in cardiac muscle. To elucidate the role of the phosphorylation of cardiac regulatory myosin light chain (MLC2) in the regulation of cardiac muscle contraction, we observed effects of calmodulin and okadaic acid, a protein phosphatase inhibitor, on myofibrillar Ca2+ sensitivity as estimated by pCa50 values obtained from pCa-tension relationships using beta-escin-skinned cardiomyocytes from Wistar rat hearts, in relation to changes in the phosphorylation of myofibrillar regulatory proteins. Whereas myofibrillar Ca2+ sensitivity tended to be progressively decreased by repeated Ca2+-activation in the absence of calmodulin (pCa50; from 5.91 to 5.86, n = 5), calmodulin (2.5 microM) significantly increased myofibrillar Ca2+ sensitivity (pCa50; from 5.92 to 6.03, n = 5, p < 0.05). Okadaic acid over 3 microM enhanced Ca2+-activated force, which was inhibited by 50 microM trifluoperazine, a calmodulin antagonist. Okadaic acid (3 microM) significantly increased myofibrillar Ca2+ sensitivity (pCa50; from 5.96 to 6.11, n = 6, p < 0.05). Whereas the phosphorylation level of troponin I was not changed by 3 microM okadaic acid, that of MLC2 was significantly increased by the same dose of okadaic acid (from 12 to 31%, n = 4, p < 0.05). These results suggest that MLC2 phosphorylation plays a partial role in the regulation of myofibrillar Ca2+ sensitivity in cardiac muscle.

Post-beta-receptor impairment in the regulation of myofibrillar Ca2+ sensitivity in tachypacing-induced canine failing heart.

Although one of the salient abnormalities in signal transduction of failing myocardium is downregulation of the beta-adrenergic receptor, the extent of presentation of downstream pathways distal to beta-receptors is misunderstood. We addressed this question in tachypacing-induced canine failing heart by assessing changes in myofibrillar Ca2+ sensitivity and troponin I phosphorylation. At a basal state, no significant difference in myofibrillar Ca2+ sensitivity was found between normal and failing hearts. Isoproterenol 8-bromo-cylic adenosine monophosphate (cAMP), and 8-bromo-cAMP isobutylmethylxantine all significantly decreased the Ca2+ sensitivity in the normal, but not in the failing, heart. EMD57033 (10 microM ), a myofibrillar Ca2+ sensitizer increased the Ca2+ sensitivity to a similar extent in both groups. The troponin I phosphorylation levels were significantly decreased in the failing heart. These results suggest that abnormalities of the beta-adrenergic signaling system exist not only at the receptor level but also at downstream steps after cAMP production.