Slash and burn management and permanent or rotation agroforestry systems: A comparative study for C sequestration by century model simulation.

Understanding the effects of agroforestry systems (AFs) on soil organic carbon (SOC) requires long-term experiments, but scenarios simulations can anticipate the potential of these systems to sequester or lose carbon (C). This study aimed to simulate the SOC dynamics in slash and burn management (BURN) and AFs using the Century model. Data from a long-term experiment implemented in the Brazilian semiarid region were used to simulate SOC dynamics under BURN and AFs situations, and the natural vegetation (NV) "Caatinga" as a reference. BURN scenarios considered different fallow periods (0, 7, 15, 30, 50 and 100 years) among cultivation of the same area. The two types of AFs (agrosilvopastoral-AGP and silvopastoral-SILV) were simulated in two contrasting conditions: (i) each one of the AFs and also NV area were permanently conducted with no rotation among these areas; and (ii) the two AFs and NV rotated among them every 7 years. The correlation coefficients (r), coefficients of determination (CD) and coefficients of residual mass (CRM) showed adequate performance, meaning that the Century model is able to reproduce the SOC stocks in the slash and burn management and AFs situations. The equilibrium points of NV SOC stocks stabilized around 30.3 Mg ha-1, as similar to the measured average of 28.4 Mg ha-1 at field conditions. The adoption of BURN without a fallow period (0 years) resulted in a reduction of 50% of SOC, approximately 20 Mg ha-1, after the first 10 years. Permanent (p) and rotating (r) AFs management systems recovered (in 10 years) fast to the original SOC stocks, resulting in higher SOC stocks than NV SOC at equilibrium. The fallow period of 50 years is necessary to recovery SOC stocks in the Caatinga biome. The simulation shows that the AFs systems increase more SOC stocks than observed in natural vegetation in long-term.

Effect of concentrate supplement to ewes on nutritive value of ingested Caatinga native forage nutritive value as affected by season.

The objective of this study was to identify by microhistological technique the reference chemical components for use as indicators of the nutritive value of Caatinga plants forage grazed by sheep throughout the year. A flock of twenty mixed-race meat ewes, multiparous, in production, with an average 34.84 ± 1.75 kg live weight and 36 months of age was assigned to supplement treatment of 0, 200, 350, and 500 g concentrate/head/day for 3 years. The experiment was designed as a randomized complete design with repeated measures over time. Supplementation with concentrate did not influence chemical composition of selected forage. In contrast, season heavily influenced diet chemical composition. Canopy stratum, season, and plant botanical family of selected species affected forage chemical composition selected by ewes. The ewes selected forage with greater nutritive value during the rainy season. Based on principal component analysis of the nutritive value of the primary forage species selected, ewes preferentially grazed plants contained greater neutral detergent fiber, acid detergent fiber, crude protein (CP), C fraction of nitrogenous compounds, and carbohydrate fractions A + B1 and C compared to the average native Caatinga herbage. Rangeland botanical composition and ewe diet varied during the year, affecting forage nutrients on offer, with the best diet selected during the rainy season because of the presence of dicotyledonous herbaceous species rich in CP as well as soluble carbohydrates and nitrogenous compounds. Concentrate supplement strategies for ewes on rangelands, such as Caatinga, should be determined by herbaceous species nutritive value during the rainy season and deep-rooted perennial dicotyledons during the dry season. These include the need to monitor ewe selection of forage species and their nutritive value, which is effectively accomplished with fecal microhistological techniques.

Corn-based or high linoleic acid flushing increases productivity of Morada Nova and Brazilian Somalis ewes / Flushing à base de milho ou alto ácido linoleico aumenta a produtividade de ovelhas Morada Nova e Somalis Brasileira

The objective of this study was to compare the corn-based (FLU), high linoleic acid flushings(LAF), and a control treatment (un supplemented, CON); two genetic groups:Morada Nova (MN) and Brazilian Somalis (BS), on the productive and reproductive performance of ewes and their lambs. A total of 156 non-pregnant ewes were supplemented three weeks before and after the breeding season. Supplementation with either FLU or LAF increased ewe body condition score (BCS) at the beginning of the breeding season and at lambing compared to CON. The BS ewes had greater body weights at the supplementation end, and BCS both at the supplementation start, and at lambing compared to MN. Similarly, ewes with three lambs per birth had greater BCS at the beginning of supplementation. They also had greater weights at the beginning of the breeding season and at lambing. Both FLU and LAF increased total lamb weight from 56 to 105 days of age compared to CON.The BS ewes had decreased prolificity and produced lower total weight of lambs at lambing, but greater 84 and 105 days after birth compared to MN. Total lambweight at birth was greater for ewes that lambed three, followed by two and then one lamb per birth. In conclusion, the high linoleic acid and high corn supplementation increase body condition score of ewes form breeding season to lambing and enhance lamb performance after 56 days of age. Although Morada Nova ewes increased prolificacy, their lambs were lighter after they reached 84 days of age.

O objetivo deste estudo foi comparar flushings à base de milho (FLU), ácido linoleico alto (FAL), e tratamento controle (não suplementado, CON);dois grupos genéticos: Morada Nova (MN) e Somalis Brasileiro (SB), sobre desempenho de ovelhas e cordeiros. Foram suplementadas 156 ovelhas não prenhes três semanas antes e após a estação de monta. Tanto FLU quanto FAL aumentaram o escore de condição corporal (ECC) de ovelhas no início da estação de monta e no parto, comparado ao CON. Ovelhas da raça SB tiveram maior peso no final da suplementação, e ECC, tanto no início da suplementação, quanto ao parto comparado ao MN. Da mesma forma, ovelhas com três cordeiros por nascimento tiveram ECC maior no início da suplementação. Elas também tiveram maiores pesos tanto no início da estação como no parto. Tanto FLU como FAL aumentaram o peso do cordeiro de 56 até 105 dias de idade comparadoao CON. Ovelhas SB diminuíram a prolificidade e produziram menor peso total de cordeiros ao parto, porém maior peso totalapós 84 e 105 dias comparado às ovelhas MN. O peso totaldecordeiros ao nascimento foi maior para ovelhas com gestação tripla, seguido por dupla, e simples. Em conclusão, a suplementação com ácido linoleico e milho aumentam o escore da condição corporal de ovelhas desde a estação de monta até o parto e a performance do cordeiro após 56 dias de idade. Embora ovelhas Morada Nova tenham aumentado a prolificidade, seus cordeiros ficaram mais leves apósos 84 dias de idade.

Corn-based or high linoleic acid flushing increases productivity of Morada Nova and Brazilian Somalis ewes / Flushing à base de milho ou alto ácido linoleico aumenta a produtividade de ovelhas Morada Nova e Somalis Brasileira

The objective of this study was to compare the corn-based (FLU), high linoleic acid flushings(LAF), and a control treatment (un supplemented, CON); two genetic groups:Morada Nova (MN) and Brazilian Somalis (BS), on the productive and reproductive performance of ewes and their lambs. A total of 156 non-pregnant ewes were supplemented three weeks before and after the breeding season. Supplementation with either FLU or LAF increased ewe body condition score (BCS) at the beginning of the breeding season and at lambing compared to CON. The BS ewes had greater body weights at the supplementation end, and BCS both at the supplementation start, and at lambing compared to MN. Similarly, ewes with three lambs per birth had greater BCS at the beginning of supplementation. They also had greater weights at the beginning of the breeding season and at lambing. Both FLU and LAF increased total lamb weight from 56 to 105 days of age compared to CON.The BS ewes had decreased prolificity and produced lower total weight of lambs at lambing, but greater 84 and 105 days after birth compared to MN. Total lambweight at birth was greater for ewes that lambed three, followed by two and then one lamb per birth. In conclusion, the high linoleic acid and high corn supplementation increase body condition score of ewes form breeding season to lambing and enhance lamb performance after 56 days of age. Although Morada Nova ewes increased prolificacy, their lambs were lighter after they reached 84 days of age.(AU)

O objetivo deste estudo foi comparar flushings à base de milho (FLU), ácido linoleico alto (FAL), e tratamento controle (não suplementado, CON);dois grupos genéticos: Morada Nova (MN) e Somalis Brasileiro (SB), sobre desempenho de ovelhas e cordeiros. Foram suplementadas 156 ovelhas não prenhes três semanas antes e após a estação de monta. Tanto FLU quanto FAL aumentaram o escore de condição corporal (ECC) de ovelhas no início da estação de monta e no parto, comparado ao CON. Ovelhas da raça SB tiveram maior peso no final da suplementação, e ECC, tanto no início da suplementação, quanto ao parto comparado ao MN. Da mesma forma, ovelhas com três cordeiros por nascimento tiveram ECC maior no início da suplementação. Elas também tiveram maiores pesos tanto no início da estação como no parto. Tanto FLU como FAL aumentaram o peso do cordeiro de 56 até 105 dias de idade comparadoao CON. Ovelhas SB diminuíram a prolificidade e produziram menor peso total de cordeiros ao parto, porém maior peso totalapós 84 e 105 dias comparado às ovelhas MN. O peso totaldecordeiros ao nascimento foi maior para ovelhas com gestação tripla, seguido por dupla, e simples. Em conclusão, a suplementação com ácido linoleico e milho aumentam o escore da condição corporal de ovelhas desde a estação de monta até o parto e a performance do cordeiro após 56 dias de idade. Embora ovelhas Morada Nova tenham aumentado a prolificidade, seus cordeiros ficaram mais leves apósos 84 dias de idade.(AU)

Produção de silagem de sorgo com diferentes doses de uréia em dois períodos de armazenamento / Sorghum silage making with differents urea doses in two storage periods

Dois experimentos foram conduzidos no delineamento inteiramente casualizado para avaliar o valor nutritivo, o perfil de fermentação de silagem de sorgo produzida com a adição de doses crescentes de uréia e dois períodos de armazenamento e determinar as frações protéicas e dos carboidratos da silagem. Foram usados silos de PVC com 50 cm de altura e 10 cm de diâmetro para o armazenamento do sorgo. No experimento I, a avaliação do valor nutritivo das silagens foi realizada através da determinação da composição química e da digestibilidade in vitro da matéria seca das silagens e, o perfil de fermentação, através da determinação dos teores de nitrogênio amoniacal, dos valores de pH e dos teores de carboidratos solúveis (CHOS) das silagens. A adição de uréia na produção da silagem de sorgo mostrou-se com potencial de minimizar perdas de matéria seca (MS) da silagem. A adição de uréia na ensilagem de sorgo aumentou os teores de proteína bruta (PB), proteína insolúvel em detergente neutro (PIDN), digestibilidade in vitro da matéria seca (DIVMS) das silagens e diminuiu os teores de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), celulose e lignina. O período de armazenamento teve efeito sobre os teores de FDN, FDA, celulose e lignina. Em relação às variáveis inerentes às características fermentativas das silagens, as doses de uréia tiveram efeito quadrático sobre o teor de nitrogênio amoniacal das silagens. Os valores de pH das silagens aumentaram linearmente. Houve efeito significativo dos períodos de armazenamento sobre o teor de nitrogênio amoniacal e valor de pH. Houve efeito de interação entre doses de uréia e período de armazenamento, apenas sobre o valor de pH. Entretanto, a adição de uréia na ensilagem de sorgo não prejudicou o perfil de fermentação das silagens e pode melhorar o valor nutritivo das mesmas. No experimento II, foram determinadas e avaliadas as frações que constituem a PB e os carboidratos totais (CHO) das silagens. As frações nitrogenadas (A, B1+B2, B3 e C) das silagens foram influenciadas pela adição de uréia, constatando-se efeito linear positivo para os teores da fração A, efeito linear negativo para as frações B1+B2, B3 e C. A análise de regressão detectou redução linear do teor de CHO em função da adição de uréia. As frações de CHO (A+B1, B2 e C) foram influenciadas pela adição de uréia, constatando-se efeito linear negativo sobre os teores da fração A+B1, efeito linear positivo sobre a fração B2 e efeito linear positivo para o teor da fração C dentro do período de 60 dias

Two experiments were conducted to evaluate the nutritive value, the profile of fermentation of sorghum silage produced with addition urea doses and two storage periods and to determine nitrogen and carbohydrates fractions of the silages. The PVC silos with 50 cm of height and 10 cm of diameter were used to sorghum storage. In the experiment I, the evaluation of the nutritional value of the silages was accomplished through the determination of the chemical composition and in vitro dry matter disappearance (IVDMD) of the silages and, the fermentation profile, through the determination of the contents of ammonia-N, values pH and WSC of the silages. The urea addition in the production of the sorghum silage was shown with potential of minimizing losses of DM of the silage. The urea addition in the sorghum ensilage increased the contents of CP, NDIP and the IVDMD of the silages and it reduced the contents of NDF, ADF, cellulose and lignin. The storage period had effect on the contents of NDF, ADF, cellulose and lignin. In relation to the inherent variables to the fermentative characteristics of the silages, the urea doses had quadratic effect on the contents of ammonia-N of the silages. The values of pH of the silages increased lineary. There was effect of the storage periods on the contents ammonia-N and pH value. There was interaction between urea doses and storage period, only on the pH value. However, the urea addition in the sorghum ensilage did not damage fermentation profile of silages and it can improve his nutritive value. In the experiment II, crude protein and CT fractions of the silages were determined and evaluated. The nitrogen fractions of the silages were influenced by the urea addition, being verified positive lineal effect for the contents of the A fraction, negative lineal effect for B1+B2, B3 and C fractions. The regression analysis detected lineal reduction of the contents of CT in function of the urea addition. The fractions of CT were influenced by the urea addition, being verified negative lineal effect on the contents of the A+B1 fraction, positive lineal effect about the B2 fraction and positive lineal effect for the content of the C fraction inside of the period of 60 days