Susceptibility of N'Dama and Boran cattle to sequential challenges with tsetse-transmitted clones of Trypanosoma congolense

Summary The susceptibility of N'Dama cattle ( Bos taurus ) to four consecutive infections with different tsetse-transmitted clones of Trypanosoma congolense was compared with that of Borans ( Bos indicus ). All animals were aged 13 months al the start of the study and had been born and raised free from trypanosomiasis under the same management and nutritional conditions, thereby limiting environmental factors that could have influenced susceptibility. While cattle of both breeds were equally susceptible to the establishment of trypanosome infections, the N'Damas exhibited superior resistance. Despite infection with virulent parasites, the N'Damas gained weight at the same rate as uninfected control animals, they did not develop anaemia to the extent that trypanocidal drug treatment was required, and all made a spontaneous recovery to normal hacmatological values within two to four months. In contrast, all the Borans needed treatment during the course of the four infections because of severe anaemia and showed markedly reduced liveweight gains. These clinical differences in the N'Damas were associated with two repcatable characteristics, namely, the ability to control parasitaemia and to'resist' anaemia, processes that did not appear to be linked. Also in contrast to the Borans. the N'Damas were able to mount accelerated haemopoietic responses, resulting in the reduced severity of anaemia following a primary infection. These findings pose the question as to whether the ability to control parasitaemia and to'resist' anaemia could be used as criteria for identifying resistant or trypanotolerant cattle.     

Standardization of a technique for analysing the frequency of parasite-specific cytotoxic T lymphocyte precursors in cattle immunized with Theileria parva

Summary A limiting dilution microculture system was optimized to quantify the frequency of Theileria parva-specific cytotoxic T lymphocyte precursors (CTLp) in peripheral blood mononuclear cells (PBMC) from immune cattle. Optimal results were obtained with responder cell input levels ranging from 2 × 10⁴/well to 6.25 × 10²/well, along with 1–5 × 10³/well stimulator cells in standard supplemented RPMI 1640 medium containing 2.5–5% T cell growth factors. Thirty-six microtitre wells were established at each responder input level. Cultures were incubated for 7 days at 38°C, at the end of which time individual wells were screened for cytotoxic activity in a 4-h ¹¹¹indium oxine-release assay. Analysis of the cytotoxicity data, by a computer-programmed maximum likelihood estimation method indicated that they conformed to the Poisson model of single-hit kinetics. Estimates of frequencies ranged from 1:3600 to 1:5275 CTLp in PBMC of eight cattle between 1 and 24 months after immunization with T. parva. By contrast, no CTLp were detected in six naïve animals analysed to a responder cell input of 10⁵/well. Split-well analysis of individual microwells showed that the CTL clones generated under limiting dilution conditions displayed exquisite specificity for parasitized cells, were genetically restricted and in some animals were parasite strain-specific.     

MEASUREMENT AND IDENTIFICATION OF PRORENIN AND RENIN IN OVARIAN FOLLICULAR FLUID FROM CATTLE AND PIG

1. In previous studies we have demonstrated and solved several methodological problems in relation to the measurement of prorenin by trypsin activation in rat, bovine, hog and horse plasma. 2. The aim of the present study was to develop a method for the measurement of prorenin in bovine and porcine ovarian follicular fluid. 3. Trypsin activation of follicular fluid generated angiotensin I immunoreactive material (AI IM) in both species. 4. The AI IM interfered with the renin assay, but could be completely removed by a cation exchange resin in a batch-wise technique. 5. The enzymatic activity of trypsin-activated prorenin and pre-existing active renin was completely inhibited by a specific inhibitor of renin. 6. The reactions were optimized and an accurate measurement of prorenin in ovarian follicular fluid was developed. 7. The existence of prorenin and renin in bovine ovarian follicular fluid was established. Prorenin and renin in porcine ovarian follicular fluid was demonstrated for the first time. 8. The ratio between ovarian follicular fluid and plasma was 43 for prorenin and 19 for active renin in cattle. The same ratios in pigs were 1.3 and 0.4, respectively. These findings indicate a species difference with respect to the amount of prorenin or active renin present in ovarian follicular fluid.     

The enzymatic degradation of bradykinin in semen of various species

Summary. The degradation of bradykinin in semen and on washed sperm cells of various species (human, pig, cattle, sheep) is mainly controlled by two peptidases, the angiotensin-converting enzyme (ACE/kininase II; E.C. 3.4.15.1) and neutral metalloendopeptidase (NEP; E.C. 3.4.24.11). In addition, minor activities of kininase I (carboxypeptidase N/CPN; E.C. 3.4.17.3) were measured exclusively in human samples. Samples of the investigated species varied considerably in their ratios of the activities of bradykinin degrading peptidases. This should be considered in any approach aimed at maintaining the promoting effect of bradykinin on sperm motility by use of enzyme inhibitors.     

Erysipelothrix rhusiopathiae serotype 5‐associated metritis in a Norwegian Red heifer

This report summarized the findings of a case of Erysipelothrix rhusiopathiae infection in a farmed Norwegian Red heifer located in the south‐east of Norway. The 2.5‐year‐old pregnant heifer was found dead after a short episode of inappetence. On gross exam, the heifer was severely dehydrated with uterine torsion. Microscopically, necrosis of the endometrium was present throughout the uterus along with presence of intralesional Gram‐positive bacteria, interstitial nephritis, and pyelonephritis. E. rhusiopathiae was isolated from the uterus and placenta and was also demonstrated by immunohistochemistry (IHC) in the uterus, placenta, and kidney. The E. rhusiopathiae isolate was further characterized as serotype 5. To the authors’ knowledge, this is the first report of bacterial metritis associated with E. rhusiopathiae serotype 5 infection. The etiology of the infection is unknown but the E. rhusiopathiae could have been a primary or opportunistic pathogen. Serotype 5 of E. rhusiopathiae has been identified in several mammalian species in recent years and could be emerging.     

Ovarian action of leptin: effects on insulin-like growth factor-I-stimulated function of granulosa and thecal cells

To test the hypothesis that leptin signals metabolic information to the reproductive system in cattle by directly affecting IGF-I-induced ovarian cell function, granulosa and thecal cells from bovine ovarian follicles were cultured for 2 d in serum-free medium with added hormones. Recombinant human leptin at 30 and 300 ng/mL had no effect on basal thecal cell steroidogenesis or thecal cell numbers. However, 300 but not 30 ng/mL of leptin attenuated (p<0.05) luteinizing hormone-induced androstenedione production by 24% in the absence of IGF-I and by 16% in the presence of IGF-I. Leptin had no effect on IGF-I-induced estradiol production in the presence of follicle-stimulating hormone (FSH), but at 100 ng/mL, leptin inhibited (p<0.05) FSH plus IGF-I-induced progesterone production and granulosa cell proliferation by 29 and 31%, respectively. Leptin did not compete for ¹²⁵I-IGF-I binding to granulosa or thecal cells, whereas unlabeled IGF-I did. In conclusion, leptin has weak inhibitory effects on gonadotropin-and/or IGF-I-induced steroidogenesis of thecal and granulosa cells.     

An inhibitor persistently decreased enteric methane emission from dairy cows with no negative effect on milk production

A quarter of all anthropogenic methane emissions in the United States are from enteric fermentation, primarily from ruminant livestock. This study was undertaken to test the effect of a methane inhibitor, 3-nitrooxypropanol (3NOP), on enteric methane emission in lactating Holstein cows. An experiment was conducted using 48 cows in a randomized block design with a 2-wk covariate period and a 12-wk data collection period. Feed intake, milk production, and fiber digestibility were not affected by the inhibitor. Milk protein and lactose yields were increased by 3NOP. Rumen methane emission was linearly decreased by 3NOP, averaging about 30% lower than the control. Methane emission per unit of feed dry matter intake or per unit of energy-corrected milk were also about 30% less for the 3NOP-treated cows. On average, the body weight gain of 3NOP-treated cows was 80% greater than control cows during the 12-wk experiment. The experiment demonstrated that the methane inhibitor 3NOP, applied at 40 to 80 mg/kg feed dry matter, decreased methane emissions from high-producing dairy cows by 30% and increased body weight gain without negatively affecting feed intake or milk production and composition. The inhibitory effect persisted over 12 wk of treatment, thus offering an effective methane mitigation practice for the livestock industries.The livestock sector is a significant source of greenhouse gas (GHG) emissions in the United States and globally (1, 2). In the United States, enteric fermentation of feed by ruminants is the largest source of anthropogenic methane emissions (0.14 Gt of CO₂ Eq. in 2012; or 25% of the total methane emissions; ref. 3). Globally, according to the most recent Intergovernmental Panel on Climate Change (IPCC) report, GHG emissions from agriculture represent around 10–12% (5.0–5.8 Gt CO₂ Eq/yr) of the total anthropogenic GHG emissions (1). In this report, livestock contribution to the global anthropogenic GHG emissions was estimated at 6.3%, with GHG emissions from enteric fermentation accounting for 2.1 Gt CO₂ Eq/yr and manure management accounting for 0.99 Gt CO₂ Eq/yr (1). The relative contribution of emissions from enteric fermentation to the total agricultural GHG emissions will vary by region depending on the structure of agricultural production and type of livestock production systems. For example, GHG from enteric fermentation were estimated at 57% for New Zealand, a country with a large, pasture-based livestock sector (4). Extensive research in recent years has provided a number of viable enteric methane mitigation practices, such as alternative electron receptors, methane inhibitors, dietary lipids, and increased animal productive efficiency (5). Methane emission in the reticulo-rumen is an evolutionary adaptation that enables the rumen ecosystem to dispose of hydrogen, a fermentation product and an important energy substrate for the methanogenic archaea (6), which may otherwise accumulate and inhibit carbohydrate fermentation and fiber degradation (7, 8). Some compounds may be effective in decreasing methane emission, but they may also decrease feed intake, fiber degradability, and animal productivity (5), or the rumen archaea may adapt to them (9). Therefore, it is important to evaluate methane mitigation strategies in long-term experiments, which for livestock experimentation requires treatment periods considerably longer than the 21–28 d, common for crossover designs. In addition, due to a variety of constraints and confounding factors of batch or continuous culture in vitro systems (5, 10), mitigation compounds, including methane inhibitors, have to be tested in vivo using animals with similar productivity to those on commercial farms. An example of the limitations of in vitro systems is a series of experiments with garlic oil. In continuous rumen culture, garlic oil was very effective in inhibiting rumen methane emission (11), but it failed to produce an effect in sheep (12). The nutrient requirements of high-producing dairy cows are much greater than those of nonlactating or low-producing cows (13) and hence any reduction in feed intake caused by a methane mitigation compound or practice would likely result in decreased productivity, which may not be evident in low-producing cows.Methane inhibitors are chemical compounds with inhibitory effects on rumen archaea. Compounds such as bromochloromethane, 2-bromoethane sulfonate, chloroform, and cyclodextrin have been tested, some successfully, in various ruminant species (5). Inhibition of methanogenesis by these compounds in vivo can be up to 60% with the effect of bromochloromethane shown to persist in long-term experiments (5, 14). However, the viability of these compounds as mitigation agents has been questioned due to concerns for animal health, food safety, or environmental impact. Bromochloromethane, for example, is an ozone-depleting agent and is banned in many countries.Among the efficacious methane inhibitors identified is 3-nitrooxypropanol (3NOP; ref. 15). This compound was part of a developmental program designing specific small molecule inhibitors for methyl coenzyme-M (CoM) reductase, the enzyme that catalyzes the last step of methanogenesis, the reduction of methyl CoM and coenzyme-B (CoB) into methane and a CoM–CoB complex (16). A continuous in vitro culture study (11) was followed by in vivo experiments in sheep (17), beef (18), and dairy cattle (19, 20), which demonstrated that 3NOP is an effective methane inhibitor. However, these experiments were conducted using nonlactating animals (17), or were short-term (<35 d; refs. 19 and 20). The rumen microorganisms have the ability to adapt to foreign agents or changes in the feeding regimen and, therefore, short-term responses are not representative of the effect of a given mitigation compound or practice in real farm conditions. McIntosh et al. (21), for example, showed that the MIC50 of essential oils doubled or tripled for a number of important rumen bacteria (Butyrivibrio fibrisolvens, Prevotella bryantii, Ruminococcus albus, Ruminobacter amylophilus), if they were adapted to the treatment for a period of 10 d. Thus, it is critically important for the success of GHG mitigation efforts to substantiate the mitigation potential of a given compound in long-term animal experiments before considering it for adoption by the livestock industries.     

Schmallenberg virus in domestic cattle, belgium, 2012

To determine prevalence of antibodies against Schmallenberg virus in adult cows and proportion of infection transmitted to fetuses, we tested serum samples from 519 cow/calf pairs in Belgium in spring 2012. Of cattle within 250 km of location where the virus emerged, ≈91% tested positive for IgG targeting nucleoprotein. Risk for fetal infection was ≈28%.     

Novel orthobunyavirus in Cattle, Europe, 2011

In 2011, an unidentified disease in cattle was reported in Germany and the Netherlands. Clinical signs included fever, decreased milk production, and diarrhea. Metagenomic analysis identified a novel orthobunyavirus, which subsequently was isolated from blood of affected animals. Surveillance was initiated to test malformed newborn animals in the affected region.