Short-term changes in nitrogen availability, gas fluxes (CO2, NO, N2O) and microbial biomass after tillage during pasture re-establishment in Rondônia, Brazil

Anthropogenic conversion of primary forest to pasture for cattle production is still frequent in the Amazon Basin. Practices adopted by ranchers to restore productivity to degraded pasture have the potential to alter soil N availability and N gas losses from soils. We examined short-term (35 days) effects of tillage prior to pasture re-establishment on soil N availability, CO₂, NO and N₂O fluxes and microbial biomass C and N under degraded pasture at Nova Vida ranch, Rondônia, Brazilian Amazon. We collected soil samples and measured gas fluxes in tilled and control (non tilled pasture) 12 times at equally spaced intervals during October 2001 to quantify the effect of tillage. Maximum soil NH₄⁺ and NO₃⁻ pools were 13.2 and 6.3 kg N ha⁻¹ respectively after tillage compared to 0.24 and 6.3 kg N ha⁻¹ in the control. Carbon dioxide flux ranged from 118 to 181 mg C–CO₂ m² h⁻¹ in the control (non-tilled) and from 110 to 235 mg C–CO₂ m² h⁻¹ when tilled. Microbial biomass C varied from 365 to 461 μg g⁻¹ in the control and from 248 to 535 μg g⁻¹ when tilled. The values for N₂O fluxes ranged from 1.22 to 96.9 μg N m⁻² h⁻¹ in the tilled plots with a maximum 3 days after the second tilling. Variability in NO flux in the control and when tilled was consistent with previous measures of NO emissions from pasture at Nova Vida. When tilled, the NO/N₂O ratio remained <1 after the first tilling suggesting that denitrification dominated N cycling. The effects of tilling on microbial parameters were less clear, except for a decrease in qCO₂ and an increase in microbial biomass C/N immediately after tilling. Our results suggest that restoration of degraded pastures with tillage will lead to less C matter, at least initially. Further long-term research is needed.     

Feed preference and growth response of juvenile Litopenaeus vannamei to supplementation of marine chemoattractants in a fishmeal‐challenged diet

This study compared the feed preference and growth response of Litopenaeus vannamei to chemoattractants. A diet with 3% fishmeal was supplemented with either 3% salmon meal (POS), 3% soy protein concentrate (NEG), 3% krill meal (KRM), 3% squid meal (SQM), 3% shrimp head meal (SHM), 3% shrimp meal (SM), 3% squid liver meal (SLM), or 5% liquid sardine hydrolysate (SAH). Shrimp with a body weight (BW) of 0.99 ± 0.08 g were stocked at 100 animals/m² in 56 tanks of 1 m³ and fed 10 times daily for 74 days. Feed preference was evaluated by feeding shrimp of 10.87 ± 1.82 g in excess twice a day for 10 days in two separate feeding trays allocated in 50 tanks of 0.5 m³. Survival reached 93.3 ± 5.80% and was unaffected by supplementation. Final BW was the highest for shrimp fed the KRM‐supplemented diet (11.97 ± 0.93 g), followed by POS (11.11 ± 0.77 g) and SQM (11.01 ± 1.17 g). Diets SHM, SM, SLM, and NEG showed a lower shrimp BW than POS, but were not statistically different among them. Shrimp fed the SAH diet achieved the lowest BW (10.06 ± 1.02 g). The highest gained yield was obtained with diets KRM and POS. No statistical difference was observed in shrimp yield among other diets. The lowest feed conversion ratio (FCR) was achieved with shrimp fed KRM (1.31 ± 0.05) when compared to diets SHM (1.47 ± 0.05), SAH (1.47 ± 0.07), and SLM (1.45 ± 0.17). Two‐by‐two comparisons indicated that shrimp preferred SHM and KRM, except when these were compared to SQM and SLM. No difference in feed preference was found between diets with SQM and SLM. SAH was the least preferred raw material in all comparisons. Results indicated that KRM acts as a powerful feeding effector and growth enhancer in fishmeal‐challenged diets for whiteleg shrimp. A dietary supplementation with 3% KRM is more effective than the same dose of any other chemoattractant evaluated.     

Comparison of hemodynamic, clinicopathologic, and gastrointestinal motility effects and recovery characteristics of anesthesia with isoflurane and halothane in horses undergoing arthroscopic surgery

OBJECTIVE: To compare hemodynamic, clinicopathologic, and gastrointestinal motility effects and recovery characteristics of halothane and isoflurane in horses undergoing arthroscopic surgery. ANIMALS: 8 healthy adult horses. PROCEDURE: Anesthesia was maintained with isoflurane or halothane (crossover study). At 6 intervals during anesthesia and surgery, cardiopulmonary variables and related derived values were recorded. Recovery from anesthesia was assessed; gastrointestinal tract motility was subjectively monitored for 72 hours after anesthesia. Horses were administered chromium, and fecal chromium concentration was used to assess intestinal transit time. Venous blood samples were collected for clinicopathologic analyses before and 2, 24, and 48 hours after anesthesia. RESULTS: Compared with halothane-anesthetized horses, cardiac index, oxygen delivery, and heart rate were higher and systemic vascular resistance was lower in isoflurane-anesthetized horses. Mean arterial blood pressure and the dobutamine dose required to maintain blood pressure were similar for both treatments. Duration and quality of recovery from anesthesia did not differ between treatments, although the recovery periods were somewhat shorter with isoflurane. After isoflurane anesthesia, gastrointestinal motility normalized earlier and intestinal transit time of chromium was shorter than that detected after halothane anesthesia. Compared with isoflurane, halothane was associated with increases in serum aspartate transaminase and glutamate dehydrogenase activities, but there were no other important differences in clinicopathologic variables between treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with halothane, isoflurane appears to be associated with better hemodynamic stability during anesthesia, less hepatic and muscle damage, and more rapid return of normal intestinal motility after anesthesia in horses undergoing arthroscopic procedures.     

Senescent leaf decomposition in a Mediterranean pear orchard

In a pear orchard, when leaf senescence occurs, nitrogen (N) is added to the soil by the fallen leaves and can be re-used by the tree after undergoing decomposition and mineralization processes. Studies on leaf decomposition and N mineralization in orchards are scarce but essential to understand the N balance in the tree–soil ecosystem in a sustainable or precision agriculture. This study aimed to quantify the contribution of pear tree senescent leaves to N cycling in the orchard and its re-cycling by the crop. ‘Rocha’ pear unlabelled leaves were incubated in situ using the litter-bag technique and ¹⁵N-enriched leaves were placed at the soil surface in undisturbed confined cores.One- to six-year-old pear trees returned to the soil between 1 kg N ha^?1 year^?1 and 6 kg N ha^?1 year^?1 from senescent leaves that decomposed at rates varying from 0.0025 day^?1 (d^?1) to 0.0047 d^?1 (estimated by both techniques, respectively). In the litter-bags, after 506–641 days, only 18–35% of initial DW was recovered in the soil, whereas in the soil cores the weight loss was higher, resulting in only 30–6% of initial DW after 398–406 d. After this period, between 36% and 110% of the initial N of the senescent leaves was recovered as organic ¹⁵N in the surface soil layer (0–7.5 cm), depending on climatic conditions, and being more prone to be absorbed by weeds.     

Growth performance of juvenile pacu (Piaractus mesopotamicus) and dourado (Salminus brasiliensis) fed with lyophilized bovine colostrum

Growth performance was evaluated in juvenile pacu (Piaractus mesopotamicus) and dourado (Salminus brasiliensis) fed diets containing 0%, 10% and 20% of lyophilized bovine colostrum for 60 days. The performance variables of weight gain, relative weight gain, feed intake, feed conversion ratio, specific growth rate, total protein intake and protein efficiency ratio were evaluated as well as apparent digestibility coefficients of protein and energy in the diets. Inclusion of bovine colostrum did not induce differences in the performance of pacu and dourado (P > 0.05), indicating that the diets were adequate and met the nutritional needs of the juveniles. The protein digestibility in both species was improved with the inclusion of the bovine lacteal secretion. Based on the variables studied, the diets with lyophilized bovine colostrum inclusion were nutritionally suitable for both pacu and dourado indicating the possibility to use this lacteal secretion as a partial substitute of dietary protein.     

Composition and fatty acid profile of milk from cows supplemented with pressed oilseed cake

This study compared the productive and nutritional parameters of milk from crossbred lactating cows managed on Panicum maximum Jacq. cv. Tanzania and with a diet supplemented with different pressed oilseed cakes. The supplements used were as follows: peanut cake, sunflower cake and palm kernel cake for replacement of soybean meal. Sixteen cows with an average weight of 544 ± 57 kg and producing 8 ± 1.4 L of milk per day were used in this study. The animals were randomly assigned to the treatments according to a Latin square design repeated over time, with four treatments, 16 animals and four experimental periods. Supplementation of the diet with peanut cake, sunflower cake and palm kernel cake compared with soybean meal in the diet of cows did not affect the average daily production or composition of the milk. The palm kernel cake promoted an increase in lauric fatty acids (C_12:0) and palmitoleic acids (C_16:1) (5.02 and 1.65%, respectively) compared with peanut cake and sunflower cake (4.13 and 4.01%, respectively). The levels of oleic fatty acids (C_18:1) were higher for the sunflower cake and palm kernel cake supplements (26.01 and 25.01%, respectively) compared with peanut cake (23.11%). The replacement of soybean meal with sunflower cake and palm kernel cake improved the nutritional quality of the milk, with lower concentrations of saturated fatty acids and higher concentrations of unsaturated fatty acids, without compromising the production or nutritional composition of the milk. © 2015 Japanese Society of Animal Science     

Effects of vaccination against brucellosis and clostridia on the intake,performance, feeding behavior,blood parameters,and immune responses of dairy heifers calves

The aim of this study was to identify possible effects of different vaccination strategies (concomitantly or not) against brucellosis and clostridia on intake, performance, feeding behavior, blood parameters, and immune responses of dairy heifers calves. Fifty heifers calves were enrolled [38 Gyr (Zebu, Bos taurus indicus) and 12 5/8 Holstein Gyr]. At 120 d of age, animals were randomly distributed among 3 groups: B (n = 18), vaccinated against brucellosis; C (n = 14), vaccinated against clostridia and CB (n = 18), vaccinated concomitantly for both. Rectal and thermographic temperatures were evaluated on days 1, 0, 1, 2, 3, 5, 7,10, 14, and 28 relatives to the vaccination day. Feed and water intake, body weight (BW), and feeding behavior were monitored daily by an electronic feeding system. Blood was sampled on days 0, 3, 7, 14, and 28, relative to the vaccination day for determination of glucose and -hydroxybutyrate (BHBA) concentrations. Blood sampled on day 0 (prevaccination) and on days 28 and 42 were used to evaluate the immune response against Brucella abortus and clostridia. There was an increase in rectal temperature between the first and the third day postvaccination in the 3 groups. The thermography revealed an increase of local temperature for 7 d on groups B and CB. Group C had increased local temperature for a longer period, lasting for up to 14 d. Dry mater intake was reduced for groups B and CB, but no alteration was observed for group C. No alterations regarding initial BW, final BW, average daily weight gain, and feed efficiency were observed. No differences were observed for the 3 vaccination groups for blood parameters throughout the evaluation period. The concomitant vaccination against brucellosis and clostridia led to lower neutralizing antibody titers against epsilon toxin of Clostridium perfringens and botulinum toxin type C of C. botulinum (C > CB > B). When cellular proliferation assay and serological tests to B. abortus were evaluated, no differences were observed between groups B and CB. The present results indicate that the concomitant vaccination against brucellosis and clostridia has no relevant impact on the intake, performance, and feeding behavior of dairy calves. However, the concomitant vaccination of vaccines against these 2 pathogens impacts animal immunity against clostridial infections.     

接种PCV2疫苗对母猪繁殖性能的影响

<正>仔猪断奶后多系统衰竭综合症(Post-weaning Multi-systemicWasting Syndrome,PMWS)首次发现在1995年和1996年,分别在加拿大和欧洲,该病为一种全球性的猪病,也是由猪圆环病毒2型(PCV2)引起的疾病综合征(也被统称为猪圆环2型病)之一。除了PMWS外,PCV2也被视为母猪繁殖障碍的病因之一。本文的目的是简要地回顾该主题的可用数据和已经公布的从接种Circovac疫苗(一种PCV2灭活苗)的母猪中获得的数据。     

Milk production,intake, digestion,blood parameters,and ingestive behavior of cows supplemented with by-products from the biodiesel industry

This study aimed to evaluate the intake, digestion, blood parameters, and feeding behavior of crossbred dairy cows (Holstein?×?Gir) managed on Panicum maximum Jacq. cv. Tanzania-1 and provided supplementation with groundnut cake, sunflower cake, or palm kernel cake (to replace soybean meal). Sixteen cows were randomly assigned in a Latin square design with four treatments and four experimental periods. The consumption of nutrients from the pasture did not vary between experimental treatments. Cows receiving the palm kernel cake supplement had a reduced crude protein, non-fibrous carbohydrate, and total digestible nutrient intake and an increase in the average consumption of ether extract. There was also a reduction in the digestibility of dry matter. The inclusion of supplements in the diet did not influence the average time spent eating, ruminating, or resting. The mean values of respiratory and heart rates showed thermal comfort during the trial period. There was a reduction in blood urea nitrogen with palm kernel cake supplementation, and the values of total protein, albumin, and glucose were also significantly different with this supplement. It is recommended that cakes of groundnut cake and sunflower cake seed be used for a total replacement of soybean meal supplements for lactating cows, but the use of palm kernel cake is not recommended.