Comparative Dynamics of Nutrient Release through Litter Decomposition in Eucalyptus grandis Hill ex Maiden and Pinus taeda L. Stands

The installation of commercial stands with exotic forest species on low fertility soils originally covered by native pastures is an unusual situation worldwide. In recent years, the area occupied by forest systems designed for pulp or wood production with immediate replanting has increased strongly in the Pampean region of South America. In this context, the study of nutrient recycling from forest litter decomposition acquires particular relevance. This work seeks to evaluate and compare the nutrient release from the decomposition of forest litter produced by 14-year-old Eucalyptus grandis Hill ex Maiden and Pinus taeda L. stands and test the applicability of a new sampling methodology in the nutrient recycling assessment. For two years, the evaluation of N, P, K, Ca, Mg, Fe, Mn, Cu and Zn dynamics during litter decomposition was carried out. In general, K concentration decreased through decomposition, meanwhile, all other nutrients showed some degree of immobilization, but this was counteracted by biomass loss for most of them. This mainly resulted in net nutrient release from litter. A higher release rate of all nutrients from P. taeda forest litter compared to E. grandis, with the exception of Mn, was verified. Fe immobilization was observed in both species showing a higher immobilization rate in E. grandis compared to P. taeda. Finally, Zn exhibited immobilization processes in E. grandis and releases in P. taeda. This might suggest higher temporal and quantitative availability of nutrients in P. taeda, due their faster return to the soil. These findings could be relevant in the development of models for sustainable management, adapting the demand for nutrients to the supply during forest rotations.

Degraded pastures in Brazil: improving livestock production and forest restoration

Degraded pasture is a major liability in Brazilian agriculture, but restoration and recovery efforts could turn this area into a new frontier to both agricultural yield expansion and forest restoration. Currently, rural properties with larger degraded pasture areas are associated with higher levels of technical inefficiency in Brazil. The recovery of 12 million ha of degraded pastures could generate an additional production of 17.7 million bovines while reducing the need for new agricultural land. Regional identification of degraded pastures would facilitate the targeting of agricultural extension and advisory services and rural credit efforts aimed at fostering pasture recovery. Since only 1% of Brazilian municipalities contain 25% of degraded pastures, focusing pasture recovery efforts on this small group of municipalities could generate considerable benefits. More efficient allocation of degraded and native pastures for meat production and forest restoration could provide land enough to fully comply with its Forest Code requirements, while adding 9 million heads to the cattle inventory. Degraded pasture recovery and restoration is a win–win strategy that could boost livestock husbandry and avoid deforestation in Brazil and has to be the priority strategy of agribusiness sector.

Osteomalacia as a result of phosphorus deficiency in beef cattle grazing subtropical native pastures in Uruguay

We investigated 2 outbreaks of osteomalacia as a result of phosphorus (P) deficiency in herds of lactating beef cows grazing subtropical native pastures in Uruguay. Cows exhibited pica, difficulty to stand and walk, rib fractures, and body weight loss even with adequate forage availability. Osteopenia and severe osteomalacia were observed on gross and histologic examination. The concentrations of bicarbonate-extractable P in soil (4.0, 4.1 mg P/kg), total P in pasture (0.9, 1.1 g P/kg), inorganic P in serum (1.0, 0.71 mmol P/L), and P in bone (73 mg P/mL) were all low. Although injectable and mineral salt supplements provided additional P in both outbreaks, these supplementary amounts were insufficient to prevent P deficiency. The P ingested by the cows from the pasture and supplements would have provided 20–55% of their daily P requirements of ~21 g P/d. Osteomalacia occurred in cattle at the 2 ranches as a result of severe P deficiency in the soil and forage, and inadequate P supplementation. Following diagnosis, control of P deficiency in beef cattle requires estimation of the amount of pasture P ingested and provision of sufficient additional supplementary P to meet the animals’ requirements.

The amazonian capim-açú is less nitrogen dependente than antelope grass to produce leaf dry matter

ABSTRACT The Maranhão floodplain is dominated by native grasses like capim-açú (Paspalum plicatulum, Mich.). Due to scarce information on nutrient demands of native species, farmers are replacing native pastures by exotic and potentially invasive species such as antelope grass (Echinochloa pyramidalis, Lam). The aim of this study was to compare the growth of capim-açú and antelope grass, under varying N and K doses, to better understand the potential of capim-açú to be used as forage. The experiment was carried out in pots, consisting of a 2 × 5 × 2 factorial scheme (2 species × 5 N doses × 2 K doses) with four repetitions, in a completely randomized design. The N doses of 0, 50, 100, 150 and 200 mg dm-3 were combined with 10 and 30 mg dm-3 K2O. The capim-açú produces higher leaf to stem ratio aboveground by using lower nitrogen and potassium doses than antelope grass. Leaf, stalk, and total dry matter production of both studied species do not respond to potassium doses.

GROWTH PERFORMANCE OF RED SOKOTO AND WEST AFRICAN DWARF GOATS FED ON NATIVE PASTURES SUPPLEMENTED WITH CONCENTRATE RATION

Six Red Sokoto (RS) and six West African Dwarf goats (WAD) aged 12 months and housed individually were reared for five months at the Small Ruminants Improvement and Multiplication Research Unit of ESUT, Abakaliki Campus. The animals were allowed to graze in the University Paddocks containing both native and introduced pastures, browse plants and leguminous herbage. The grazing period lasted from 0800 - 1200 hours in the morning and 1500 - 1700 in afternoon daily and between these two periods they were fed supplemental diets. The results showed that there were highly significant difference amongst the members of the genotypes whose mean body weights were ranged from 24.71 $ 0.083 - 40.750 0.55 (RS) and from 14,98+ 0.47 - 27.52 0.73kg (WAD). The heights at the withers and body length measurements also showed a highly significant increase (P< 0.01) in the genotype during the period. The two genotypes differed remarkably (P< 0.01) from each other with RS being superior in body weight and height at the withers, and body length. However, the measurements taken of the thigh size and hearth girth circumference revealed no real difference between the RS and WAD (P >0.05). The findings indicate anthropometric areas requiring genetic improvement among the WAD, and at the same time serve as a pointer to the amount of response shown by the Maradi goats to management in the wet humid tropical environment to which it was being exposed.

9 Fixed timed artificial insemination during different seasons in Argentina (2016–2019)

The objective of this work was to evaluate pregnancy rates in buffaloes subjected to fixed-time AI (FTAI) during the year in Argentina. The data analysed was collected between 2016 to 2019 in a farm located in Paso Florentin City (27°20′33″ latitude and 58°08′27″ longitude) in Corrientes, Argentina. The animals were grazing native pastures (Andropogon lateralis, Paspalum almum). Ten fixed-time AI (FTAI) sessions were performed, 6 within the favourable season (BS, March–June) and 4 in the outbreeding season (OBS; September–December). Murrah and Mediterranean breed (n=141) buffaloes were used. All animals were healthy, without anatomical alterations and with normal reproductive tracts. Heifers (H), adult females with calf (AFC), and dry buffaloes (DB) were used. The average (±s.d.) weight of the animals were 459.0±37.5kg, 581.3±53.6kg, and 583.3±53.1kg, respectively. The presence of corpus luteum (CL) or a dominant follicle (≥8mm) at the beginning of the protocol was recorded. BS ovulation induction: Ovsynch (n=182); Day 0 gonadotrophin-releasing hormone (GnRH; 100μg, busereline acetate), Day 7 prostaglandin F2α (150μg, cloprostenol), Day 9 GnRH and FTAI 16h after the last GnRH injection. For the OBS (n=85): Day 0 intravaginal device (700mg of P4) + oestradiol benzoate (0.2g), Day 8 removal of the device + prostaglandin F2α + oestradiol cypionate (0.1g) + eCG (400IU) and Day 10 FTAI (52–56h) after device removal. Semen from 5 bulls of proven fertility was used, and the same technician performed all the inseminations. A specifically designed format to record the data were used and the average±s.d. of the physiological and the meteorological parameters were calculated. Pregnancy was detected 40 days after FTAI using ultrasonography. Comparison within variables were performed using ANOVA and Tukey test, with InfoStat-Statistical Software. A total of 267 inseminations were performed, and the overall pregnancy rate (PR) was 37.45% (100/267). Comparing BS with OBS, PR were 40.7% (74/182) and 30.6% (26/85) (P&lt;0.005). Heifers had a higher PR (51.5%) than suckled buffaloes (38.8%) and dry buffaloes (20%) during the BS (P&lt;0.05). In the OBS, there were no differences among categories on PR for [36.36 (4/11) H, 28.57 (12/42) AFC, 19.51 (8/41) DB; P&gt;0.05]. The presence of a CL at the beginning of the FTAI protocol had a positive effect on PR during the year in all categories [31.79% (55/173) H, 40.42 (38/94) AFC, 21.51 (17/79) DB vs. 25.45% (28/110) H, 29.68 (19/64) AFC, 19.56 (9/46) DB; P&lt;0.05]. Season had a significant effect over PR, but rain, temperature, daylight, and humidity did not differ during the year. These results show the feasibility of FTAI in water buffalo, confirm that it is possible to maintain the PR during the year, and demonstrate successful performance of protocol induction in cyclic females during the year. More research is needed to improve PR in buffaloes in Argentina, to explain the low results in suckled and dry adult buffaloes, and to analyse the effect of meteorological conditions over the breeding performance of the animals.

113 Mineral Supplementation Effects in Stocker Cattle Performance Grazed on Wheat Seeded Native Pastures

One way to extend the grazing season in the southeast United States is to plant cool-season forages into native pastures to provide additional forages for the winter and spring grazing. The objective of this study was to evaluate the effects of two different medicated (Monensin) supplementation types, with or without protein, on stocker calves grazing native pasture overseeded with wheat through the months of February to May. Cross-bred steers (n = 36; BW = 291.76 kg ± 29.92) and heifers (n = 29; BW = 288.17 kg ± 25.22), sired primarily by Hereford bulls, were assigned to two treatment groups at two locations blocked by sex and weight. All mineral supplementation was provided ad libitum. The first supplementation consisted of a commercial loose mineral (Advanced Mineral Performance Technology (AMPT); ADM; Quincy, Illinois), and the second was a commercial protein block (MoorMan’s, Mintrate Blonde Block RU; ADM; Quincy, IL) containing 42.0% Crude Protein. Average Daily Gain was compared using PROC MIX with the main effects: treatment, pasture, gender, and their interactions. The starting weights of the treatment groups were not different (P = 0.996). No significant interactions (P &lt; 0.05) were detected and only the main effects will be reported. Steers gained more (P &lt; 0.0001) than heifers (1.25 kg ± 0.025 kg vs. 0.96 kg ± 0.029 kg, respectively). ADG for the mineral was 1.14 kg ± 0.027 kg, compared to 1.06 kg ± 0.028 kg for the protein block (P &lt; 0.05). Differences in ADG was observed between pastures (P &lt; 0.07). At 124 days the final body weight of heifers averaged 119.56 kg and the steers averaged 154.70 kg. These results indicate that the mineral improved ADG over the block supplementation.

Epidemiological aspects of natural poisoning by Prosopis juliflora in ruminants in semiarid areas of the state of Bahia, Brazil, invaded by the plant

ABSTRACT: Poisoning by Prosopis juliflora (mesquite) leads to neurological signs, cachexia and death, mainly in cattle and goats. Although the uncontrolled spread of mesquite in the Caatinga biome (biological invasion), which alters the epidemiological conditions of intoxication by this plant, has been proved for approximately 20 years, strategies for its control and prophylaxis still remain out of date. These new epidemiological conditions have allowed the uncontrolled consumption of large amounts of in natura mesquite pods by ruminants for long periods in invaded pastures, thus resulting in increased history of poisoning. This study aimed to describe the new epidemiological aspects of P. juliflora poisoning in cattle and goats, 78 years after the introduction of this plant in the country, with emphasis on its degree of invasion, and to update the control and prophylaxis measures of this intoxication and the mapping of areas of outbreak occurrence in the semiarid region of the state of Bahia, Brazil. Seven outbreaks of natural mesquite poisoning, two in goats (OB 1 and OB 2) and five in cattle (OB 3, OB 4, OB 5, OB 6, and OB 7), were studied in loco in the municipalities of Juazeiro, Iaçu, Tucano, Santa Teresinha, Barra do Mendes, Barra and Tabocas do Brejo Velho. In the studied outbreaks, clinical-epidemiological (OB 1 to OB 7) and histopathological (OB 1, OB 2, OB 3, and OB 5) findings were compatible with mesquite poisoning, and this was the first anatomopathological proof of poisoning by this plant in this state. In addition, in the state of Bahia, disease occurs in an area approximately three times larger than previously known. On the farms investigated, mesquite introduction occurred between 1980 and 2005, through the single planting of an average of 33 seedlings. Since then, propagation of this plant has occurred progressively, with gradual invasion of native pastures, which enabled the evaluation of plant spread (biological invasion) on these farms 15 (OB 2), 25 (OB 7), 30 (OB 5 and OB 6), 35 (OB 3) and 40 (OB 1 and OB 4) years after its introduction. Historical information on the introduction and spread of mesquite in the state of Bahia had never been analyzed. In 2020, a degree of mesquite invasion an average 59.57% was verified in the pastures of the seven farms where the outbreaks occurred. The great biological invasion capacity of this plant drew attention, especially in OB 5. The high degree of mesquite invasion observed (new epidemiological conditions) justifies the increased number of cases of poisoning observed in this study. Processing of P. juliflora pods (grinding) was not carried out on any farm (OB 1 to OB 7), and ruminants uncontrollably consumed large amounts of pods in natura for long periods in invaded pastures, which allowed massive dispersal of seeds through feces over decades. The main factors responsible for the gradual invasion of pastures by mesquite over time were absence of crop management plans (silvicultural treatments) and lack of knowledge by producers on disease etiology. Given the new epidemiological conditions, restriction of animal access to in natura pods in pastures and supply of mesquite bran are crucial for the control and prophylaxis of this poisoning, as consumption of in natura pods had a strong correlation with the high degree of invasion in the pastures where the seven outbreaks occurred. Additionally, although the commercialization of pods and exploitation of wood of mesquite trees can provide livestock farmers with extra income - being the correct management for areas invaded by this plant, such practice is either not yet known or not carried out technically or satisfactorily by farmers. In addition to being a threat to the Caatinga’s biodiversity, the increasing invasion of semiarid areas by mesquite 78 years after its introduction in the Northeast region of Brazil, is a risk for herds, since the occurrence of poisoning outbreaks may become more frequent. Therefore, it is highly advisable that effective measures be adopted to control P. juliflora propagation.