Marta Gomes da Rocha

Differential capacitance of liquid/liquid interfaces: effect of electrolytes present in each phase

The effect of electrolyte type and concentration on the differential capacitance of the 1,2-dichloroethane/water interface has been measured. The results show that the differential capacitance is controlled by the pair ion (1)–counter-ion (2), where 1 and 2 denote the different phases. At constant organic electrolyte composition the capacity increases in the order, F– MTMA+ > TBA+ > TOA+, TPB– > TCPB–. In very dilute solutions, the effects are not noticeable.

Efeito de sistemas de alimentação no ganho de peso e desempenho reprodutivo de novilhas Nelore acasaladas aos 17/18 meses

Using a linear statistical model (GLM/SAS) the reproductive performance and growth of 480 Nellore heifers were evaluated from the age of 7.5 to 17/18 months under four feeding systems during the dry period (96/05 to 96/10): Brachiaria brizantha cv. Marandu pasture (B); Brachiaria brizantha cv. Marandu pasture + Anipro (BA); Pennisetum americanum cv. (L.) Leeke (Pearlmillet) (M) and Brachiaria brizantha cv. Marandu pasture + Sal Ouro (BS). At the end of supplementation all heifers were moved to a paddock of Panicum maximum cv. Mombaca pasture, 1 AU/ha, from 96/10 until the end of the mating season (97/03 to 97/05). Parameters like liveweight (LW), body condition score (BCS), liveweight daily gain (LDG), age at mating (AM), pregnancy rate (PR) and age of the dam (AD) were determined. Besides these variables pregnant and non-pregnant heifers were also evaluated for scores of conformation (Cs), precocity (Ps) and muscularity (Ms). The systems BA and M registered significantly differences with major LW, LDG and BCS values after the dry season compared to systems B and BS. At the beginning of the mating season LW values from B, BA and M were different of BS system. At the end of the mating season no differences could be detected among the four systems regarding LDG, BCS, AM, and AD. No significant effect on the PR averages of the four feeding systems B, BA, M e BS was registered (22,2%, 24,2%, 20,7% e 13,8%). Significant differences (P<0.01) between pregnant and non-pregnant Nellore heifers could be detected for LW, BCS, AM, LDG, Cs, Ps, and Ms.

Suplementação energética na recria de bezerras de corte mantidas em pastagem de inverno

This work was carried outo to evaluate the effect of levels of energetic supplementation in productive and reproductive performance of sixty-four Charolais heifers and their crosses with Nellore, mantained in cultivated pasture of black oat (Avena strigosa Schreb) plus Italian ryegrass (Lulium mulktiflorum Lam.). The treatments considered supplementation of 0; 0.7 and 1.4% of the live weight (LW)/day of rice bran associated with citric pulp, in the proportion of 1:1. A continuous grazing system with variable stocking rate was used, to maintain 1500 kg/ha of DM in herbage mass in all treatments. The following parameters were evaluated: average daily gain, stocking rate, live weight gain, body condition, pelvic area, weight at puberty and age at puberty, hip height and estimated intake of DM. The supplementation increased average daily gain, stocking rate and live weight gain. Heifers kept only on pasture had lower body conditions and showed lower heat percentage than heifers supplemented with 0.7 and 1.4% of LW/day with no differences (P>0.05) between the 0.7 and 1.4% levels. The percentage of heifers showing heat until 16 months of age was 9.1; 68.7 and 70.6%, respectively. The supplementations levels did not affect pelvic area, age at puberty and hip height. The estimated intake of DM was lower for the level of 1.4 % LW/day.

Produção de forragem e retorno econômico da pastagem de aveia e azevém sob pastejo com bezerras de corte submetidas a níveis de suplementação energética

It was evaluated the forage production from black oat (Avena strigosa Schreb) plus italian ryegrass (Lolium multiflorum Lam) mixture under grazing with beef heifers of Charolais breed and their crosses with Nellore submitted to following treatments: 0, 0.7, and 1.4% live weight/day of supplementation of rice bran plus citrus pulp (1:1). Daily dry matter accumulation rate (TA), botanical composition, forage losses and economic return of the different levels of supplementation were evaluated. The treatments with supplementation increased TA, however, the supplement level of 1,4% did not differ from the 0% level. Forage mass losses represented 2.61, 1.91, and 1.41% of the live weight/day for 0, 0.7, and 1.4% supplementation levels, respectively. The total costs (C) were 289.49, 477.17, and 749.49 R

Sistemas de alimentação na produção de cordeiros para abate aos 28 kg

/ha. The gross incomes (GI) were of 551.46, 723.29, and 872.56 R

Comportamento ingestivo e desempenho de ovinos em pastagem de azevém anual (Lolium multiflorum Lam.) com diferentes massas de forragem

/ha. The net incomes were 261.49, 255.15, and 122.62 R

Recria de novilhas de corte com diferentes níveis de suplementação energética em pastagem de aveia preta e azevém

/ha. The GI/C ratio were 1.90, 1.54, and 1.16 for the treatments 0, 0.7 and 1.4% LW/day, respectively.

Avaliação de espécies forrageiras de inverno na Depressão Central do Rio Grande do Sul

The objective of this trial was to study the performance of ewes and lambs as well as the characteristics of carcass of lambs in different feeding systems. Eighteen lambs, 24 hours after birth, were randomly assigned with their mothers to one of the following treatments: RP - ryegrass (Lolium multiflorum) pasture; FNCP - feedlot with no creep feeding; and FCP - feedlot with creep feeding. The ryegrass pasture was managed in order to not limit the dry matter intake of the grazing animals with an average supply of 12 kg of dry matter per 100 kg of live weight. Animals on FNCP treatment received a diet containing 50% of sorghum silage + 50% of concentrate [11.5% crude protein (CP) and 64.4% of total digestible nutrients (TDN). Animals on FCP treatment received a diet containing 50% of sorghum silage + 25% of concentrate (8.2% CP and 60.6% TDN) and after they reached 21 days of age were fed an amount of concentrate (18% CP and 70% TDN) equal to 3% of the live weight. Average daily weight gains of 300 g/day and hot carcass yield greater than 51% were obtained by nursing lambs on either ryegrass pasture or feedlots. Data from the present trial showed no significant differences among treatments in production and carcass characteristics of lambs slaughtered with 28 kg of live weight.

Sistemas de Alimentação Pós-Desmama de Bezerras de Corte para Acasalamento com 14/15 Meses de Idade

The objective of this trial was to evaluate ingestive behaviour and performance of sheep grazing Italian ryegrass (Lolium multiflorum Lam.) pasture with different herbage mass (HM): low HM: 1,000 - 1,200 kg/ha of DM (LHM); medium HM: 1,400-1,600 kg/ha DM (MHM); high HM 1,800-2,000 kg/ha DM (HHM). A completely randomized design with three treatments and two replicates (paddocks) per treatment was used. Data were submitted to polynomial regression analysis in function of the actual HM observed in each experimental unit: 1,136.8, 1,190.9, 1,359.2, 1,375, 1,556, and 1,739.1 kg/ha DM. Leaf blade and pseudostem masses, forage and leaf blade allowances, sward and pseudostem heights, leaf blade depth, and average daily gain all increased linearly from LHM to HHM while the opposite was observed for stocking and bite rates. However, no HM effect was found for herbage intake, times spent grazing, ruminating and idle, amount of daily bite, bite mass, body condition score gain, body weight gain per hectare, and feed efficiency. The range of HM evaluated showed no differences in body weight gain per hectare with similar conversion efficiency of forage in animal product. The depth of leaf blade layers is the most important variable affecting sheep performance.

CARACTERÍSTICAS PRODUTIVAS E QUALITATIVAS DE HÍBRIDOS DE MILHO PARA PRODUÇÃO DE SILAGEM

An experiment was conducted to evaluate the rearing of beef heifers with different levels of wheat bran supplementation, on oat (Avena strigosa Schreb) + annual ryegrass (Lolium multiflorum Lam) pasture. One hundred nine Charolais and Charolais crossbreed Nellore heifers, with initial weight (LW) of 158 kg, were used. The supplementation levels were: SS - animals fed oat + annual ryegrass without supplementation; S 0.5 - animals fed 0.5% of LW/day of supplementation; S 1.0 - animals fed 1.0% LW/day of supplementation; S 1.5 - animals fed 1.5% of LW/day of supplementation. The grazing period was from July 10th to November 02nd with continuous grazing and forage offer of 10 kg dry matter (DM)/100 kg LW. The variables studied were average daily weight gain (ADG), body condition (BC), stocking rate (SR) and weight gain per ha (LWG). The supplementation levels affected the ADG, on a different way during the pasture cycle. Average ADG wasof 0.751; 0.894; 0.809 and 0.936 kg/animal/day for SS, S-0.5, S-1.0 e S-1.5 heifers, respectively. BC gain was higher for supplemented heifers, 0.8 points vs 0.5 points for heifers maintained only on pasture. The SR increased linearly during the grazing period, for the S 1.5, resulting in greater LWG than for the SS and S 0.5. The substitution rate of forage intake by the supplement consumption and the addition on total DM intake were determinant for the supplemented heifers performance.