In grass–legume swards, biologically fixed nitrogen (N) from the legume can support the N requirements of the grass, but legume N fixation is suppressed by additional fertilizer N application. This ...study sought to identify a fertilizer N application rate that maximizes herbage and N yields, N fixation and apparent N transfer from white clover to companion grasses under intensive grazing at a site with high soil‐N status. During a 3‐year period (2011–2013), swards of perennial ryegrass and of perennial ryegrass–white clover, receiving up to 240 kg N ha−1 year−1, were compared using isotope dilution and N‐difference methods. The presence of white clover increased herbage and N yields by 12–44% and 26–72%, respectively. Applications of N fertilizer reduced sward white clover content, but the effect was less at below 120 kg N ha−1. The proportion of N derived from the atmospheric N fixation was 25–70%. Nitrogen fixation ranged from 25 to 142 kg N ha−1 measured using the isotope dilution method in 2012 and from 52 to 291 kg N ha−1 using the N‐difference method across all years. Fertilizer N application reduced the percentage and yield of fixed N. Transfer of N from white clover to grass was not confirmed, but there was an increased N content in grass and soil‐N levels. Under intensive grazing, the maximum applied N rate that optimized herbage and N yields with minimal effect on white clover content and fixation rates was 60–120 kg N ha−1.
The superior milk production efficiency of Jersey (JE) and Jersey × Holstein-Friesian (JE × HF) cows compared with Holstein-Friesian (HF) has been widely published. The biological differences among ...dairy cow genotypes, which could contribute to the milk production efficiency differences, have not been as widely studied however. A series of component studies were conducted using cows sourced from a longer-term genotype comparison study (JE, JE × HF, and HF). The objectives were to (1) determine if differences exist among genotypes regarding gastrointestinal tract (GIT) weight, (2) assess and quantify whether the genotypes tested differ in their ability to digest perennial ryegrass, and (3) examine the relative abundance of specific rumen microbial populations potentially relating to feed digestibility. Over 3 yr, the GIT weight was obtained from 33 HF, 35 JE, and 27 JE × HF nonlactating cows postslaughter. During the dry period the cows were offered a perennial ryegrass silage diet at maintenance level. The unadjusted GIT weight was heavier for the HF than for JE and JE × HF. When expressed as a proportion of body weight (BW), JE and JE × HF had a heavier GIT weight than HF. In vivo digestibility was evaluated on 16 each of JE, JE × HF, and HF lactating dairy cows. Cows were individually stalled, allowing for the total collection of feces and were offered freshly cut grass twice daily. During this time, daily milk yield, BW, and dry matter intake (DMI) were greater for HF and JE × HF than for JE; milk fat and protein concentration ranked oppositely. Daily milk solids yield did not differ among the 3 genotypes. Intake capacity, expressed as DMI per BW, tended to be different among treatments, with JE having the greatest DMI per BW, HF the lowest, and JE × HF being intermediate. Production efficiency, expressed as milk solids per DMI, was higher for JE than HF and JE × HF. Digestive efficiency, expressed as digestibility of dry matter, organic matter, N, neutral detergent fiber, and acid detergent fiber, was higher for JE than HF. In grazing cows (n=15 per genotype) samples of rumen fluid, collected using a transesophageal sampling device, were analyzed to determine the relative abundance of rumen microbial populations of cellulolytic bacteria, protozoa, and fungi. These are critically important for fermentation of feed into short-chain fatty acids. A decrease was observed in the relative abundance of Ruminococcus flavefaciens in the JE rumen compared with HF and JE × HF. We can deduce from this study that the JE genotype has greater digestibility and a different rumen microbial population than HF. Jersey and JE × HF cows had a proportionally greater GIT weight than HF. These differences are likely to contribute to the production efficiency differences among genotypes previously reported.
An experiment was undertaken to investigate the effect of white clover inclusion in grass swards (GWc) compared with grass-only (GO) swards receiving high nitrogen fertilization and subjected to ...frequent and tight grazing on herbage and dairy cow productivity and enteric methane (CH4) emissions. Thirty cows were allocated to graze either a GO or GWc sward (n=15) from April 17 to October 31, 2011. Fresh herbage 16kg of dry matter (DM)/cow and 1kg of concentrate/cow were offered daily. Herbage DM intake (DMI) was estimated on 3 occasions (May, July, and September) during which 17kg of DM/cow per day was offered (and concentrate supplementation was withdrawn). In September, an additional 5 cows were added to each sward treatment (n=20) and individual CH4 emissions were estimated using the sulfur hexafluoride (SF6) technique. Annual clover proportion (±SE) in the GWc swards was 0.20±0.011. Swards had similar pregrazing herbage mass (1,800±96kg of DM/ha) and herbage production (13,110±80kg of DM/ha). The GWc swards tended to have lower DM and NDF contents but greater CP content than GO swards, but only significant differences were observed in the last part of the grazing season. Cows had similar milk and milk solids yields (19.4±0.59 and 1.49±0.049kg/d, respectively) and similar milk composition. Cows also had similar DMI in the 3 measurement periods (16.0±0.70kg DM/cow per d). Similar sward and animal performance was observed during the CH4 estimation period, but GWc swards had 7.4% less NDF than GO swards. Cows had similar daily and per-unit-of-output CH4 emissions (357.1±13.6g of CH4/cow per day, 26.3±1.14g of CH4/kg of milk, and 312.3±11.5g of CH4/kg of milk solids) but cows grazing GWc swards had 11.9% lower CH4 emissions per unit of feed intake than cows grazing GO swards due to the numerically lower CH4 per cow per day and a tendency for the GWc cows to have greater DMI compared with the GO cows. As a conclusion, under the conditions of this study, sward clover content in the GWc swards was not sufficient to improve overall sward herbage production and quality, or dairy cow productivity. Although GWc cows had a tendency to consume more and emitted less CH4 per unit of feed intake than GO cows, no difference was observed in daily or per-unit-of-output CH4 emissions.
A 4-year (2010–2013) plot study was undertaken to evaluate the effect of nitrogen (N) fertilizer rate (0, 60, 120, 196 and 240 kg N/ha/year) on seasonal responses and species persistency in ...frequently and tightly grazed (⩽4 cm) grass-only (GO) and grass white clover swards (GWc). Increasing N application rate increased herbage removed and pre-grazing sward height. Cows frequently grazed the GWc tighter than the GO. Increasing N rate reduced clover content, especially during the warmest months of the year, but less so up to 120 kg N/ha/year. The GWc had greater amounts of herbage removed than GO in the May–September period but the effect was less as N rate increased. Cumulative herbage removed from GWc was greater than GO swards receiving the same N rate and herbage quality was better in GWc than GO. Such effects were reduced as swards aged and with increasing N rate. It was concluded that under frequent and tight grazing management: (1) clover inclusion increased annual herbage removed; (2) herbage removed from GWc swards receiving no N was the same as the GO sward receiving 240 kg N/ha, and greater for the 240 GWc swards than the 240 GO swards; (3) clover inclusion benefits were mainly from summer onwards; (4) the management strategy applied in the current experiment may be capable of alleviating the detrimental effect of N fertilizer on clover, to a point between 60 and 120 kg N/ha.
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•The IPCC 2019 Tier 2 equations predict methane emission adequately.•The knowledge of DE improves the accuracy of CH4 prediction.•Hay-based diets reduce digestibility, and ...consequently, a measured DE should be applied.•Local values of the CH4 conversion factor (Ym) and DE are proposed for the Mediterranean area.
The study aimed to evaluate Intergovernmental Panel on Climate Change (IPCC) Tier 2 (2006 and 2019) to predict enteric CH4 emissions from lactating cows fed Mediterranean diets. The effects of the CH4 conversion factor (Ym; CH4 energy loss as a percentage of gross energy intake) and digestible energy (DE) of the diet were evaluated as model predictors. A data set was created using individual observations derived from 3 in vivo studies on lactating dairy cows housed in respiration chambers and fed diets typical of the Mediterranean region based on silages and hays. Five models using different Ym and DE were evaluated following a Tier 2 approach: (1) average values of Ym (6.5%) and DE (70%) from IPCC (2006); (2) average value of Ym (5.7%) and DE (70.0%) from IPCC (2019; 1YM); (3) Ym = 5.7% and DE measured in vivo (1YMIV); (4) Ym = 5.7 or 6.0%, depending on dietary NDF, and DE = 70% (2YM); and (5) Ym = 5.7 or 6.0%, depending on dietary NDF, and DE measured in vivo (2YMIV). Finally, a Tier 2 model for Mediterranean diets (MED) was derived from the Italian data set (Ym = 5.58%; DE = 69.9% for silage-based diets and 64.8% for hay-based diets) and validated on an independent data set of cows fed Mediterranean diets. The most accurate models tested were 2YMIV, 2YM, and 1YMIV with predictions of 384, 377, and 377 (g of CH4/d), respectively, versus the in vivo value of 381. The most precise model was 1YM (slope bias = 1.88%; r = 0.63). Overall, 1YM showed the highest concordance correlation coefficient value (0.579), followed by 1YMIV (0.569). Cross-validation on an independent data set of cows fed Mediterranean diets (corn silage and alfalfa hay) resulted in concordance correlation coefficient of 0.492 and 0.485 for 1YM and MED, respectively. The prediction of MED (397) was more accurate than 1YM (405) in comparison with the corresponding in vivo value of 396 g of CH4/d. The results of this study showed that the average values proposed by IPCC (2019) can adequately predict CH4 emissions from cows fed typical Mediterranean diets. However, the use of specific factors for the Mediterranean area, such as DE, improved the accuracy of the models.
Pasture management that considers pasture growth dynamics remains an open question. Conceptually, such management must allow for grazing only after the recuperation of the pasture between two ...separate timely grazing periods when pasture reaches optimum recovery, as per the first law of Voisin's rational grazing system. The optimum recovery period not only implies a pasture with better nutritional value and higher biomass yield but one that also reduces the production of enteric methane (CH4) to improve the grazing efficiency of cattle. Therefore, this study aimed to evaluate three different recovery periods (RP) of mixed grasses on the grazing behaviour of heifers, as well as herbage selectivity, herbage yield and nutritional value, in vitro degradability and CH4 production. Based on these criteria, three pasture RPs of 24 (RP24), 35 (RP3) and 46 (RP46) days were evaluated in six blocks using a randomized block design. At each predetermined RP, samples of the pasture were taken before the animals were allowed to graze. Right after collecting the pasture samples, heifers accessed the pasture during 4 h consecutively for grazing simulation and behavioural observations. We also measured the bite rate of each animal. The pasture growing for 24 days had the highest biomass production, best nutritional value, best efficiency of in vitro CH4 relative emission (ml) per DM degraded (g) and bite rate of the three RPs. Heifers all selected their herbage, irrespective of RP, but with different nutritional value and higher in vitro degradability. However, this did not change the production of in vitro CH4. Considering the growth conditions of the area where the study was performed, we recommend the shorter RP24 as the most suitable during the summer season. The study's findings support the idea of management intervention to increase the quality of grazing systems.
The aim of this study was to investigate whether social rank (SR) and stability in the order of entrance to the milking parlour are associated with production traits. The study was conducted on a ...dairy farm where cows (n = 215) were managed in three groups according to lactation stage (group 1: 78 cows, 0–100 days in milk (DIM); group 2: 65 cows, 101–200 DIM and group 3: 72 cows, >200 DIM). SR was calculated from observations made from agonistic behaviour performed at the water troughs and feed bunks of each pen (n = 3). The animals were classified into three levels of dominance based on at least five clear interactions, resulting in: 61 dominant, 75 intermediate and 69 subordinate cows based on SR. Stability in the order of entry was estimated as the standard deviation of the entry position. SR was weakly correlated with milk yield, urea and protein content in milk. The results showed that stable cows had higher milk production and entered the milking parlour after the non-stable animals. Stability in the order of entry to the milking parlour was not affected by SR. Overall, the use of milking facilities appears to be associated with production traits rather than SR.
Leishmaniasis is a complex group of parasitic infectious diseases caused by intracellular protozoa of the genus
. It is a zoonosis mainly transmitted by the bite of infected female
or
sandflies. ...Clinical manifestations of leishmaniasis are diverse and can range from asymptomatic presentations to disseminated systemic disease. Cutaneous leishmaniasis is endemic in more than 80 countries in the world, having a predominance in tropical and subtropical regions. Although the majority of cases follow a classic development, an increasing number of new and rare variants of cutaneous leishmaniasis have been reported. These variants should be suspected as a cause of diverse clinical presentations, especially in endemic regions and travelers, being a diagnostic challenge for physicians. We present a case of atypical cutaneous leishmaniasis found as a single verrucous plaque of eight months of evolution in the left posterior thigh of a 35-year-old man, who presented mild pruritus. The patient reported shrimp farming as his main occupational activity and was living in a rural region surrounded by forest on the Pacific coast of Ecuador. On dermatological examination, a single 4 x 5 cm verrucous plaque with irregular borders and a scaly erythematous violaceous aspect was found. Histopathological analysis revealed the presence of lymphohistiocytic inflammatory infiltrate with plasmocytes and granulomatous inflammation. On the Giemsa stain, intracellular amastigotes (Leishman-Donovan bodies) were observed. The treatment consisted of intramuscular meglumine antimoniate, presenting significant improvement on follow-up.
The effect of sward type, grass only (GO) or grass white clover (GWc), on lactating dairy cow feeding behaviour, herbage depletion rate and rumen function was investigated in rotationally ...strip-grazed swards at a daily herbage allowance of 17kg dry matter (DM)/cow/day, in two experiments. In 2011, eight rumen-cannulated cows were blocked into two groups and allocated to each sward type for a 14-day period in a change-over design (2 sward types×2 periods) on three occasions: late spring, summer, and autumn. Feeding behaviour, rumen pH and rumen volatile fatty acids and ammonia contents were measured. Following a continuous design, in 2012 feeding behaviour and herbage depletion rate measurements were undertaken at similar times to those in 2011 over 2–3 weeks in late spring, summer and autumn. Twenty-six (spring) and 36 (summer and autumn) cows were used. Grazing sward height (GSH) was measured five times/day. The percentage of grazed vegetative units, and the extended tiller height, free leaf lamina, tiller DM weight and tiller leaf DM weight of perennial ryegrass (ryegrass) tillers were estimated four times/day. During late spring, summer and autumn, sward white clover content (DM basis) was 7.5%, 8.8% and 30.9%, respectively, in 2011, and 18.0%, 29.7% and 30.6%, respectively, in 2012. In 2011 cows had similar grazing times on both sward types. Cows on GWc spent less time ruminating than cows on GO. Cows had similar total volatile fatty acids on both swards but the isoacids and d-lactic acid percentages, ammonia content and rumen pH were higher in autumn for cows grazing GWc. In 2012, cows on GWc grazed for longer in late spring, ruminated for less time in summer and for less time at night in autumn compared to cows grazing the GO sward. Both sward types had similar post-grazing sward heights and sward height depletion rates, except during morning grazing in autumn, when GWc had a greater sward height depletion rate. A similar percentage of grazed ryegrass tillers was observed between sward types, but the percentage of ryegrass grazed was greater than the percentage of white clover grazed in the GWc swards. The ryegrass tillers in the GWc swards were smaller than those in the GO swards but had similar depletion rates. The GWc swards influenced cow feeding behaviour and rumen characteristics with increased effect in autumn because of an increase in white clover content and a decrease in ryegrass quality.
•White clover had no effect on cow’s grazing behaviour, but reduced ruminating time.•White clover altered rumen volatile fatty acids contents and increased rumen pH.•Sward white clover content increased as the season progressed.•White clover effects were stronger latter on the season.
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