Effects of pregrazing herbage mass in late spring on enteric methane emissions, dry matter intake, and milk production of dairy cows.

Few studies have examined the effects of fresh forage quality on enteric methane (CH4) emissions of dairy cows under grazing conditions. The aim of the current study was to evaluate the effects of 2 contrasting forage qualities induced by different pregrazing herbage masses in late spring on enteric CH4 emissions and milk production of grazing dairy cows. The experiment was conducted as a crossover design with 24 lactating Holstein Friesian dairy cows randomly assigned to 1 of 2 treatments in 2 experimental periods. Each period had a duration of 3wk (2wk for diet adaptation and 1wk for measurements), and the interval between them was 2wk. Treatments consisted of 2 target pregrazing herbage masses [2,200 and 5,000kg of dry matter (DM)/ha above 3cm], generated by different regrowth periods, corresponding to low (LHM) and high (HHM) herbage mass treatments, respectively. Daily herbage allowance (Lolium perenne) for both treatments was 20kg of DM per cow measured above 3cm. Enteric CH4 emissions were individually determined during the last week of each period using the sulfur hexafluoride tracer technique. Daily herbage intakes by individual cows during the CH4 measurement weeks were estimated using the n-alkanes technique. During the CH4 measurement weeks, milk yield and body mass were determined twice daily, whereas milk composition was determined once in the week. The LHM pasture had a higher crude protein concentration, lower neutral detergent fiber and acid detergent fiber concentrations, and higher in vitro digestibility, with a lower proportion of ryegrass pseudostems, than the HHM pasture. Cows offered the LHM pasture had greater herbage (+13%) and total DM (+12%) intakes, increased milk (+13%) and energy-corrected milk (+11%) yields, and tendencies toward higher milk protein (+4.5%) and higher milk urea nitrogen (+15%) concentrations than their counterparts offered the HHM pasture. No differences were found between treatments in total daily CH4 production. However, the LHM treatment reduced enteric CH4 emissions per unit of milk yield (-11%) and enteric CH4 energy as a percentage of ingested gross energy (-9%) and tended to reduce CH4 per unit of dry matter intake (-8.2%) and energy-corrected milk yield (-10%) compared with the HHM treatment. The results from this study suggest that a grazing management that favors better quality pasture, as was the case of the LHM pasture in late spring compared with the HHM pasture, increases milk production of grazing dairy cows and reduces enteric CH4 emissions per unit of milk produced, constituting a viable CH4 mitigation strategy.

Meta-analysis of the effect of pasture allowance on pasture intake, milk production, and grazing behavior of dairy cows grazing temperate grasslands.

Daily pasture allowance (PA) is defined as the product of pregrazing pasture mass and offered area, and is the major grazing management factor determining pasture utilization per unit area and daily performance of grazing dairy cows. The objective of the present study was to perform a meta-analysis reviewing the effect of PA on pasture intake, milk production, milk composition, and grazing behavior of dairy cows. Experiments studying the effect of PA on pasture intake or milk production, which eventually included milk composition or grazing behavior data, or both, were selected to create a database. Papers were selected only if at least 2 PA were compared under the same experimental conditions, particularly the same pasture mass (i.e., where PA levels were only obtained through changes in daily offered area). The final database included 97 PA comparisons reported in 56 papers. For analytical purposes, the database was subdivided into 3 subsets that varied according to the estimation height (EH) at which PA was determined; that is, PA above ground level (PA0 subset), PA above 2.5 to 3.5 cm (PA3 subset), and PA above 4 to 5 cm (PA5 subset). Statistical analyses were conducted independently on the PA0, PA3, and PA5 subsets and on the whole database (global analysis) by using linear and nonlinear mixed-model procedures. The curves, either exponential, quadratic, or linear, describing the effects of PA on pasture intake, milk production, or grazing behavior of dairy cows are conceptually similar, whatever the EH. The equations describing these curves are, however, specific for each EH. Accordingly, from typical low to high PA, the increase in pasture intake (0.13 vs. 0.21 vs. 0.28 kg/kg of PA), milk production (0.11 vs. 0.17 vs. 0.24 kg/kg of PA), and milk solids production (0.008 vs. 0.010 vs. 0.013 kg/kg of PA) per kilogram of increase in PA was lower for PA0 than for PA3, and for PA3 than for PA5. Grazing time increased from low to medium PA and did not vary from medium to high PA. Pasture intake rate seemed to increase from low to medium PA because of greater bite mass, whereas it increased from medium to high PA because of greater biting rate. The present meta-analysis demonstrated that the general relationship between PA and any dependent variable is quite strong and independent of EH. This suggests no specific relationship for some parts of the world or methodology approach, with a high portability of the global equations calculated here. These results are useful for improving grazing management and modeling on pasture-based dairy systems.

[Prognostic factors in severe traumatic brain injury]. / Factores pronósticos del traumatismo craneoencefálico grave.

OBJECTIVE: To describe the factors associated to mortality of patients with severe traumatic brain injury (TBI). DESIGN: A retrospective observational study was made of patients with severe TBI covering the period between 1 January 2007 and 31 December 2010. SETTING: Virgen de la Vega Hospital, Salamanca (Spain). PATIENTS: All patients hospitalized during the consecutive study period. MAIN VARIABLES OF INTEREST: The dependent variable has been the death rate, while the independent variables were divided into two groups: epidemiological and clinical. RESULTS: The mean patient age was the 50.84 years; 75.5% were males. The average score on the Glasgow Coma Scale (GCS) was 5.09, and the average Injury Severity Score (ISS) was 30.8. Higher mortality was observed in older patients with a higher ISS score. A total of 68.1% of the patients in which intracranial pressure (ICP) was monitored showed intracranial hypertension (ICH). The mortality rate in patients with severe TBI was 36.8%, and was associated mainly to a lower GCS score, the existence of hyperglycemia, coagulopathy, hypoxemia, the presence of mydriasis and shock. The independent mortality indicators in patients with severe TBI were the existence of mydriasis (OR: 32.75), the GCS score (OR: 2.65) and hyperglycemia (OR: 6.08). CONCLUSIONS: The existence of mydriasis, the GCS score and hyperglycemia should be taken into account as prognostic factors in TBI patients.

Soil intake of lactating dairy cows in intensive strip grazing systems.

Involuntary soil intake by cows on pasture can be a potential route of entry for pollutants into the food chain. Therefore, it appears necessary to know and quantify factors affecting soil intake in order to ensure the food safety in outside rearing systems. Thus, soil intake was determined in two Latin square trials with 24 and 12 lactating dairy cows. In Trial 1, the effect of pasture allowance (20 v. 35 kg dry matter (DM) above ground level/cow daily) was studied for two sward types (pure perennial ryegrass v. mixed perennial ryegrass-white clover) in spring. In Trial 2, the effect of pasture allowance (40 v. 65 kg DM above ground level/cow daily) was studied at two supplementation levels (0 or 8 kg DM of a maize silage-based supplement) in autumn. Soil intake was determined by the method based on acid-insoluble ash used as an internal marker. The daily dry soil intake ranged, between treatments, from 0.17 to 0.83 kg per cow in Trial 1 and from 0.15 to 0.85 kg per cow in Trial 2, reaching up to 1.3 kg during some periods. In both trials, soil intake increased with decreasing pasture allowance, by 0.46 and 0.15 kg in Trials 1 and 2, respectively. In Trial 1, this pasture allowance effect was greater on mixed swards than on pure ryegrass swards (0.66 v. 0.26 kg reduction of daily soil intake between medium and low pasture allowance, respectively). In Trial 2, the pasture allowance effect was similar at both supplementation levels. In Trial 2, supplemented cows ate much less soil than unsupplemented cows (0.20 v. 0.75 kg/day, respectively). Differences in soil intake between trials and treatments can be related to grazing conditions, particularly pre-grazing and post-grazing sward height, determining at least in part the time spent grazing close to the ground. A post-grazing sward height lower than 50 mm can be considered as a critical threshold. Finally, a dietary supplement and a low grazing pressure, that is, high pasture allowance increasing post-grazing sward height, would efficiently limit the risk for high level of soil intake, especially when grazing conditions are difficult. Pre-grazing and post-grazing sward heights, as well as faecal crude ash concentration appear to be simple and practical tools for evaluating the risk for critical soil intake in grazing dairy cows.

Meta-analysis of the effect of pregrazing pasture mass on pasture intake, milk production, and grazing behavior of dairy cows strip-grazing temperate grasslands.

Grazing management is a key factor in pasture-based dairy systems, which can be improved given advanced knowledge of the effects of pregrazing pasture mass (PM) on the performance of dairy cows. The aim of this study was to quantify the effects of PM on the pasture intake, milk production, milk composition, and grazing behavior of strip- or rotational-grazing dairy cows, based on a meta-analysis of published research papers. A database was created that included experiments in which the effects of PM on pasture intake and milk production of dairy cows were studied. Papers were selected only if at least 2 PM were compared under similar experimental conditions, particularly the same pasture allowance (SPA). The final database included 15 papers with 27 PM comparisons. For analytical purposes, the database was subdivided into 3 subsets that varied according to the estimation height at which pasture allowance was determined; that is, where PM were compared at the SPA above ground level (SPA(0) subset), above 2 to 3 cm (SPA(3) subset), and above 4 to 5 cm (SPA(5) subset). Statistical analyses were conducted on the entire database (global analysis) and within each subset using linear model procedures. An interaction between PM and estimation height was found for pasture intake and milk production in the global analysis. On the basis of the predictive equations, pasture intake increased by 1.58 kg of dry matter/d per tonne increase in PM when PM were compared at SPA(0), was not affected by PM when PM were compared at SPA(3), and decreased by 0.65 kg of dry matter/d per tonne increase in PM when PM were compared at SPA(5). This is consistent with the effect of PM on milk production, which was positive and negative (1.04 and -0.79 kg/t of PM, respectively) when PM were compared at SPA(0) and SPA(5), respectively. Grazing time was only slightly affected by PM, irrespective of estimation height, because the effect of PM on pasture intake was mainly dependent on the variation in pasture intake rate. Pasture intake rate increased with increasing PM at SPA(0) but decreased with increasing PM at SPA(5). This meta-analysis clearly demonstrates that the effects of PM on pasture intake, milk production, and behavior of strip-grazing dairy cows depend largely on the height at which the PM and pasture allowance are measured. These results have methodological implications for future grazing research because it can be recommended that PM be compared at similar levels of pasture availability (i.e., at the same pasture allowance above 2 to 3 cm) to avoid possible misinterpretations of results. They also reveal the benefits of improving grazing management and intake prediction through modeling in pasture-based dairy systems.

Substitution rate and milk yield response to corn silage supplementation of late-lactation dairy cows grazing low-mass pastures at 2 daily allowances in autumn.

Feed costs in dairy production systems may be decreased by extending the grazing season to periods such as autumn when grazing low-mass pastures is highly probable. The aim of this autumn study was to determine the effect of corn silage supplementation [0 vs. 8 kg of dry matter (DM) of a mixture 7:1 of corn silage and soybean meal] on pasture intake (PI), milk production, and grazing behavior of dairy cows grazing low-mass ryegrass pastures at 2 daily pasture allowances (PA; low PA=18 vs. high PA=30 kg of DM/cow above 2.5 cm). Twelve multiparous Holstein cows were used in a 4 × 4 Latin square design with 14-d periods. Pre-grazing pasture mass and pre-grazing plate meter pasture height averaged 1.8 t of DM/ha (above 2.5 cm) and 6.3 cm, respectively. The quality of the offered pasture (above 2.5 cm) was low because of dry conditions before and during the experiment (crude protein=11.5% of DM; net energy for lactation=5.15 MJ/kg of DM; organic matter digestibility=61.9%). The interaction between PA and supplementation level was significant for PI but not for milk production. Supplementation decreased PI from 11.6 to 7.6 kg of DM/d at low PA and from 13.1 to 7.3 kg of DM/d at high PA. The substitution rate was, therefore, lower at low than at high PA (0.51 vs. 0.75). Pasture intake increased with increasing PA in unsupplemented treatments, and was not affected by PA in supplemented treatments. Milk production averaged 13.5 kg/d and was greater at high than at low PA (+1.4 kg/d) and in supplemented than unsupplemented treatments (+5.2 kg/d). Milk fat concentration averaged 4.39% and was similar between treatments. Milk protein concentration increased from 3.37 to 3.51% from unsupplemented to supplemented treatments, and did not vary according to PA. Grazing behavior parameters were only affected by supplementation. On average, daily grazing time decreased (539 vs. 436 min) and daily ruminating time increased (388 vs. 486 min) from 0 to 8 kg of supplement DM. The PI rate was 6g of DM/min lower in supplemented than in unsupplemented treatments (17 vs. 23 g of DM/min). The high milk yield response to supplementation may be related to a cumulative effect of the low-mass pasture (low PI) and the low quality of the pasture, which strongly limited energy supply in unsupplemented cows.

Utilização da cápsula esplênica de bovino na ceratoplastia lamelar em coelhos / The use of bovine esplenic capsule in lamellar keratoplasty with rabbits / Ultilización de capsula esplénica de bovino en la queratoplastía lamelar en conejos

Para reparo de ceratectomias superficiais de 15 coelhos, foi utilizada cápsula esplênica de bovino conservada em glicerina a 98%. Os animais foram separados em cinco grupos de igual número e submetidos às observações clínicas e histopatológicas ao final do 3, 7, 15 ,30 e 60 dias de pós-operatório (PO). Os animais apresentaram boa evolução clínica, com presença de blefaroespasmo e neovascularização de intensidade moderada nas fases iniciais, com regressão e desaparecimento nos períodos intermediários e tardios de observações. O material implantado ocasionou edema de córnea, infiltração de polimorfonucleares, neoformação vascular e mínima reação inflamatória. O que permitiu regeneração do tecido corneal aos 30 dias de PO. A cápsula esplênica de bovinos conservada em glicerina a 98% foi eficiente na reparação de feridas lamelares em córnea de coelhos.

A 98 per cent-glycerin-preserved bovine capsule was used to fix superficial ceractomonies in rabbits. . The animals were separated into five groups of equal number, and submitted to both clinical and histological observation at the end of the 3rd, 7th, 15th, 30th, and 60th (PO) postoperative days. The animals presented good clinical evolution, moderate blefaroespasm and neovascularization in the former stages, regression and disappearing in the intermediate and latter observation ones. The implanted material caused corneal edema, nuclear polymorphous infiltration, neovascularization and minimum inflammatory reaction, which allowed the regeneration of the corneal tissue in 30 days. The 98%-glycerin-preserved bovine capsule was efficient in the repairing of the lamellar wounds in rabbits´cornea.

Para el reparo de ceratectomías superficiales de 15 conejos, fue utilizada cápsula esplénica de bovino conservada en glicerina a 98%. Los animales fueron separados en cinco grupos de igual número y sometidos a las observaciones clínicas e histopatológicas al final del 3, 7, 15, 30 y 60 días de posoperatorio (PO). Los animales presentaron buena evolución clínica, con presencia de blefaroespasmo y neovascularización de intensidad moderada en las fases iniciales, con regresión y desaparición en los períodos intermediarios y tardíos de observaciones. El material implantado ocasionó edema de córnea, infiltración de polimorfonucleares, neoformación vascular y mínima reacción inflamatoria. Lo que permitió regeneración de tejido corneal a los 30 días de PO. La cápsula esplénica de bovinos conservada en glicerina a 98% fue eficiente en la reparación de heridas lamelar en córnea de conejos.