Sulfur amino acid requirements for pullets in growth and pre-laying trials

Context To obtain a good performance of the hens in the laying phase, adequate nutrition in the growth and pre-laying phase is necessary, especially for meeting amino acid requirements that are related to development of reproductive organs (ovary and oviduct). Aims The objective of the present study was to predict the requirements for methionine (Met) plus cystine (Cys) from the growth of the body, feathers and reproductive organs of laying hens. Methods The model estimates Met+Cys requirements as the relationship between the deposition of Met+Cys into three compartments (body, feathers, and reproductive organs) and their utilisation efficiency. The efficiency of utilisation was determined by a linear regression between Met+Cys deposition and intake for pullets aged 14–28, 56–70 and 98–112 days. Protein weight and deposition in the body and feathers were determined by the comparative slaughter method. The Gompertz function was used to model body, feathers, ovary, oviduct and liver weight against age. Key results Our results showed that the inclusion of parameters descriptive of the growth of reproductive organs and the correction for feather losses in the model enabled Met+Cys requirements for growth in pre-laying trials to be predicted with a greater precision. Conclusions The model developed in this study for determining the Met+Cys requirements for Dekalb White pullets could be extended, provided the necessary adjustments are made, to other amino acids, strains and species. Implications Meeting Met+Cys requirements in the phase of maximum growth of the reproductive organs (weeks) contributes to the uniformity of the age when the pullets reach sexual maturity and, consequently, start the egg production.

140 A comparison of in vitro embryo production between heifers and lactating Holstein donors without superstimulation

Bovine oocyte donor age seems to have an important role on in vitro embryo production. Therefore, the aim of this study was to compare cumulus-oocyte complex (COC) recovery, cleavage, and blastocyst rates between heifers and lactating Holstein donors. A total of 89 animals (heifers: n=60, 11 to 17 months of age; lactating cows: n=29, 60 to 180 days in milk) were used in this experiment. Ovum pickup (Day −1) was performed on a random day of the oestrous cycle without superstimulation by a single technician. Conventional or sexed semen were used for IVF (Day 0). Cleavage and blastocyst rates were evaluated on Days 3 and 7, respectively. Cleavage was determined when structures had 4 or more cells and blastocyst rate included grades I and II blastocysts. Continuous data were analysed by t-test, and binomial data were analysed by Fischer’s exact test. A total of 1,289 COC were recovered from lactating cows (n=509) and heifers (n=777). Total and viable COC per donor were higher (P<0.05) in lactating cows (total=17.55±13.08; viable=11.24±8.9) than heifers (total=12.95±5.39; viable=7.88±4.08). The percentage of viable COC was similar (P>0.05) in lactating cows (64.04%; 326/509) and heifers (60.87%; 473/777). Cleavage rate was higher (P<0.0001) in lactating cows (58.74%; 299/509) than in heifers (45.05%; 350/427). Cleavage rate was similar (P>0.05) with conventional and sexed semen in heifers (conventional=37.68%; 52/138; sexed=46.63%; 298/639) and cows (conventional=55.05%; 49/89; sexed=59.52%; 250/470). Blastocyst rate was higher (P<0.0001) in lactating cows (19.84%; 101/509) than in heifers (8.49%; 66/777). Conventional semen had a higher (P<0.0001) blastocyst rate (18.11%; 24/138) than sexed semen (6.57%; 42/639) in heifers. However, there was no difference (P>0.05) in blastocyst rate between conventional (24.71%; 22/89) and sexed semen (18.8%; 79/420) in lactating cows. Blastocyst/cleaved structures ratio was higher (P<0.05) in heifers using conventional (46.15%; 24/52) compared with sexed (14.06%; 42/298) semen. However, in lactating cows there was a tendency (P<0.1) for higher blastocyst/cleaved structures ratio using conventional (44.89%; 22/49) compared with sexed semen (31.6%; 79/250). In conclusion, a higher number of total and viable COC were aspirated from Holstein lactating cows than heifers. Furthermore, cleavage and blastocyst rates were higher in lactating cows than in heifers. Conventional semen gave more embryos than did sexed semen in heifers but not in cows. Overall, oocytes from Holstein lactating donors are more suitable for in vitro embryo production than are those from heifer donors.

The effect of feed protein content on the uniformity of production in laying hens

The objective of this research was to describe the effect of dietary protein content on the uniformity of egg production in ISA-Brown and Hy-Line laying strains. Six dietary protein levels (120–220 g protein/kg feed) were each fed to 16 individually caged hens, per treatment and strain, during the first 6 weeks of the trial from 28 weeks of age. During the second phase, from 35 weeks, only one feed was offered, this containing 175 g protein/kg. Egg production, feed intake, egg weight, egg output and changes in bodyweight were measured. Some birds were sampled before the trial began, after 6- and again after 10-weeks for carcass analysis. Maximum egg output differed between strains but the marginal response to dietary protein was the same in both strains, the coefficients of response being 220 mg protein/g egg output and 9.0 g per kg bodyweight. The coefficient of variation in egg output was low in both strains fed the highest protein feed but increased as the dietary protein level dropped, with the biggest increase occurring in outputs between birds fed 140 and 120 g protein/kg. These increases were particularly marked in the ISA strain, being almost twice as high as those of the Hy-Line strain. Similarly the lowest coefficients of variation in daily food intake were on the highest protein feeds, with a 2- to 3-fold increase on the lowest dietary protein levels, but with both strains in this case showing similar degrees of uniformity. Variation in body lipid content was higher in the ISA strain between dietary treatments. Uniformity in egg output is increased at the highest intakes of dietary protein because the amino acid requirements of an increasing proportion of the population are met by these higher protein contents. As the protein supply becomes marginal and then deficient uniformity is decreased not only because the most demanding individuals cannot consume sufficient to achieve their potential, but also because birds differ in their ability to deposit excess energy as body lipid when attempting to consume sufficient of a feed limiting in protein. This ability to fatten differs not only between individuals within a population but between strains, as shown in the differences between the two strains used in this trial.

60 Reproductive Performance After Timed Artificial Insemination Followed by Timed Embryo Transfer of In Vitro-Produced Embryos in Beef Cattle

The combined use of timed AI (TAI) and embryo transfer (TET) has the potential to increase reproductive efficiency in beef cattle. This study evaluated reproductive performance in beef cattle after TAI followed by TET of in vitro-produced embryos at the onset of the breeding season. A total of 476 multiparous non-suckling Bos taurus females (body condition scores of 2.9 ± 0.4 on 1 to 5 scale) were oestrous synchronized with 2 mg of oestradiol benzoate (IM) and a 1.9-g intravaginal progesterone release device (Day –11), which was removed on Day –2, followed by 0.48 mg of sodium cloprostenol, 400 IU of eCG, and 0.5 mg of oestradiol cypionate (IM). In experiment I [no heat detection (HD), or no HD, n = 387], TAI was carried out 48 h later (Day 0), whereas in experiment II (after HD, n = 89), AI was performed 12 h after the onset of oestrus up to 48 h after intravaginal insert removal, when remaining females were inseminated (Day 0). Day-7 blastocysts produced by IVF from abattoir-derived oocytes were individually transferred (TET) 7 days after TAI (Day 7) to 186/387 and 44/89 females in experiments I and II, respectively, ipsilateral to the corpus luteum. Then, fertile mature Bos taurus bulls were introduced on Day 12 into the herds (1:25) up to Day 90. Determinations of pregnancy outcome after TAI, TAI+TET or natural mating, twinning rates, and pregnancy losses were done by ultrasonography and rectal palpation on Days 30, 60, and 125. Data were analysed by the Chi-squared test (P < 0.05). Pregnancy rates (Day 30) were lower after TAI (104/201, 51.7%) than after TAI+TET (126/186, 67.7%) with no HD (experiment I), but similar between TAI (32/45, 71.1%) and TAI+TET (30/44, 68.2%) after HD (experiment II). Twinning rates were lower in TAI groups with no HD (6/104, 5.8%) and after HD (2/32, 6.2%) than in TAI+TET groups with either no HD (42/126, 33.3%) or with HD (14/30, 46.7%). Overall pregnancy was similar between groups after the end of the breeding season: 90.0% (181/201) and 90.3% (168/186) for TAI and TAI+TET with no HD, and 84.4% (38/45) and 84.1% (37/44) for TAI and TAI+TET after HD. Pregnancy losses were higher after TAI+TET with no HD (27/126, 21.4%) than TAI+TET after HD (3/30, 10.0%), and TAI with (2/32, 6.3%) or without (9/104, 8.7%) HD. The TAI+TET with no HD resulted in fewer fetuses per served (0.69) and pregnant (1.30) female than TAI+TET after HD (0.89 and 1.44), whereas TAI with no HD had fewer fetuses than TAI after HD per served (0.50 v. 0.69) but not per pregnant female (1.05 v. 1.03), with both being lower than the TAI+TET groups. In summary, TET after TAI with no HD increased pregnancy and twinning rates. Also, heat detection increased pregnancy rates after TAI and twinning rates after TAI+TET. The TAI+TET combination may be advisable for reproductive schemes with no HD, whereas no benefit of TAI+TET was seen over TAI regarding pregnancy rate if TAI is coupled with HD, but HD may increase prolificacy after TAI+TET. The economics of the use of TAI+TET is under evaluation, by assessing calving, weaning, and postnatal weight gain rates between groups.

l-Arginine supplementation improves rats' antioxidant system and exercise performance

Reactive species have great importance in sports performance, once they can directly regulate energy production, muscular contraction, inflammation, and fatigue. Therefore, the redox control is essential for athletes' performance. Studies demonstrated that l-arginine has an important role in the synthesis of urea, cell growth and production of nitric oxide, moreover, there are indications that it is also able to induce benefits to muscle antioxidant system through the upregulation of some antioxidant enzymes, and by inhibiting some pathways of reactive species production. Therefore, the aim of this study was to evaluate the effects of l-arginine supplementation on performance and oxidative stress of male rats (trained or not), submitted to a single session of high intensity exercise. Forty male Wistar rats were divided into four groups, control (C), control+l-arginine (C + A), trained (T), and trained+l-arginine (T + A). The aerobic training was conducted for 8 weeks. Data of maximum speed and time from tests were used as indicators of performance. Variables related to oxidative stress and antioxidant system were also evaluated. Aerobic training was capable to induce enhancements on animals' exercise performance and on their redox state. Additionally, supplementation improved rats' physical performance on both groups, control and trained. Different improvements between groups on the antioxidant capacity were observed. Nevertheless, considering the ergogenic effect of l-arginine and the lack of all positive adaptations promoted by the exercise training, untrained animals may be more exposed to oxidative damages after the practice of intense exercises.

Description of a model to optimise the feeding of amino acids to growing pullets

1. A nutrition model is described that may be used to optimise the amino acid nutrition of laying-type pullets prior to the onset of lay. It is not a method of optimising lifetime laying performance. 2. The potential growth and composition of the body, feathers, ovary and oviduct are described from hatching to the age at which sexual maturity is attained, from which the daily amino acid and energy requirements for the average individual in the population can be calculated. 3. There are two parts to the approach used, the first being a description of the model itself and the second being a description of how the required information was gathered. A number of assumptions made in developing the model are discussed. 4. The rates of maturing of the body, feather-free body and body protein of the DeKalb pullets used were shown to be constant at 0.017/d and those of feathers at 0.02/d. These are considerably slower than those of the oviduct and ovary (0.139 and 0.084/d respectively). The ovary attained a higher mature weight (78.4 vs. 58.7 g) than the oviduct. 5. The age at which the growth of the reproductive organs is initiated in the model is defined by the user. The daily amount of threonine required to meet the requirements for maintenance and potential growth of the developing tissues and organs is calculated for each day of the growing period from hatching to the age at which the first egg is laid. A method of calculating the required daily concentration of threonine in the feed is described, from which a feeding programme may be derived. 6. For the model to produce an optimum economic feeding programme for a population of laying-type pullets, more information than is available from this study is required. These issues are discussed in the paper.

10 EFFECT OF ESTRADIOL BENZOATE OR hCG ON DAY 22 AFTER TIMED ARTIFICIAL INSEMINATION ON THE CORPUS LUTEUM SIZE, PROGESTERONE CONCENTRATION, AND PREGNANCY RATE IN RESYNCHRONIZED BEEF HEIFERS

This study aimed to compare the effects of 2 inducers of new follicular wave [oestradiol benzoate (EB) or hCG] administrated at onset of resynchronization protocols initiated 22 days after the first timed AI (TAI) of beef heifers. We evaluated the effect of treatments on corpus luteum (CL) development, serum progesterone (P4) concentrations, and pregnancy rates. A total of 467 grazing Brangus heifers, with 24- to 26-months, 320 ± 10 kg of body weight, and 3.2 ± 0.5 body condition score, were utilised. The resynchronization protocol began 22 days after the first TAI (Day 22). Heifers were randomly allocated into 1 of 3 groups: EB (n = 199), hCG (n = 101), or control untreated (n = 167). The EB- and hCG-treated heifers received an intravaginal P4 device (Procliclar, 0.75 g of P4; Hertape, Brazil) and an IM treatment with 1 mg of EB (Benzoato HC, Hertape) or 1000 IU of hCG (Vetecor 5000, Hertape), respectively. On Day 30, P4 device was removed, and the pregnancy diagnosis was performed. At this time heifers had the CL area (cm2) determined by ultrasound and seric P4 concentration evaluated by chemiluminescence assay. The assay sensitivity was 0.1 ng mL–1, and the intra- and interassay coefficients of variation were 7.9 and 10.6%, respectively. Nonpregnant heifers after the first TAI (EB = 97, hCG = 36) received intramuscularly 150 μg of sodium cloprostenol (Veteglan Luteolítico, Hertape) and 1 mg of oestradiol cypionate (Cipionato HC, Hertape). The second TAI was performed 48 to 52 h after the P4 device removal. On Day 62, heifers were submitted to a second pregnancy diagnosis. No effect of the body condition score (P = 0.28) was observed on the first and second pregnancy per AI. Pregnancy rates after the first TAI were higher (P = 0.03) on hCG-treated heifers (64.4%) than EB (51.3%) or the control group (58.7%). The EB group determined greater (P = 0.04) pregnancy rate after the second TAI (49.5%) than the hCG group (22.2%). The cumulative pregnancy rates were similar (P = 0.46) between groups [EB (72.4%) and hCG (68.3%)]; however, both were greater (P < 0.05) than the control group (58.6%). Heifers treated with hCG (3.42 ± 0.76) presented greater CL area at Day 30 (P < 0.05) than the EB (2.44 ± 0.57) and control (2.61 ± 0.61) groups. The treatment with hCG 22 days after TAI determined greater (12.43 ± 3.48; P < 0.05) serum P4 concentrations on Day 30 than the EB (6.92 ± 3.04) and control (7.29 ± 2.45) groups. Therefore, the use of hCG at the beginning of resynchronization protocol 22 days after the TAI increased pregnancy rate following the first TAI. However, the use of 1 mg of EB determined greater pregnancy rate after the second TAI, and no detrimental effects on CL development, P4 concentration, and on first TAI pre-established pregnancy.

Marine reservoir effect on the Southeastern coast of Brazil: results from the Tarioba shellmound paired samples

On the Southeastern coast of Brazil the presence of many archaeological shellmounds offers a great potential for studying the radiocarbon marine reservoir effect (MRE). However, very few such studies are available for this region. These archaeological settlements, mostly dating from 5 to 2 kyr cal BP, include both terrestrial and marine remains in good stratigraphic context and secure association, enabling the comparison of different carbon reservoirs. In a previous study the chronology of the Sambaqui da Tarioba, located in Rio de Janeiro state, Brazil, was established based on marine mollusc shells and charcoal samples from hearths, from several layers in two excavated sectors. We now compare the different materials with the aim of studying the MRE in this region. Calibration was performed with Oxford software OxCal v4.2.3 using the marine curve Marine13 with an undetermined offset to account for local corrections for shell samples, and the atmospheric curve SHCal13 for charcoal samples. The distribution of results considering a phase model indicates a ΔR value of -127 ± 67 (14)C yr in the 1 sigma range and the multi-paired approach leads to a mean value of -110 ± 94 (14)C yr.

REGULATORY INCENTIVES TO PROMOTE THE USE OF PHOTOVOLTAIC SYSTEMS IN BRAZIL

The use of photovoltaic solar energy for electricity generation has been even more considered in many countries worldwide as an excellent alternative to reduce the man-made environmental impacts, especially those associated with climate changes. In countries such as Japan, Germany, USA and other European countries, specific regulatory mechanisms have been developed to stimulate its use either through governmental programs or financial and/or tax incentives. The main common reasons on these programs are the diversification of energy sources traditionally used, namely the need to adopt a sustainable energy model, the encouragement of the photovoltaic equipment industry, an affordable technology, and a concern with the environment, mainly to the reduction of CO2 emissions. In the Brazilian case, despite the large solar resource potential, many things still need to be done and, since then only a small number of initiatives were undertaken to encourage solar photovoltaic energy, but still very small when compared to the countries mentioned above. In this sense, this paper has the purpose of presenting the evolution of the regulatory incentives concerned to the use of photovoltaic solar energy in Brazil over the years.

69 EFFECTS OF CELL TYPE, PRE-ACTIVATION PROTOCOL, AND CULTURE CONDITIONS ON DEVELOPMENT OF PORCINE HANDMADE CLONED EMBRYOS

Despite the rather successful and widespread use of cloning in various species, distinct cell types from the same species and even the same genotype display differences in blastocyst yield. Moreover, variations in the protocol for embryo production can influence development to the blastocyst stage and subsequent fetal development. The aim of this study was to evaluate the effect of 2 cell types and 2 embryo pre-activation protocols with or without the presence of FCS in the in vitro culture medium on development of handmade pig cloned embryos to the blastocyst stage. Cumulus-oocyte complexes recovered from sow ovaries were in vitro-matured for 38 to 40 h. Denuded matured oocytes selected by the presence of a polar body had the zona pellucida removed in a 0.2% protease HEPES-buffered solution +25% FCS, followed by manual bisection and UV screening of enucleated halves using Hoechst stain. Clone embryo reconstruction was performed using a phytohemoagglutinin solution to adhere 2 cytoplasts and a somatic cell. Adipocyte-derived mesenchymal stem cells (ADMSC) from a Yorkshire pig or granulosa cells (GC) from an Ossabaw pig were used as nuclear donors. Following electrical fusion, couplets were pretreated with a brief exposure to cytochalasin B (CB) or cytochalasin B + cycloheximide (CB+CX) in the presence of serum before the electrical activation (Naruse et al. 2007 Theriogenology 68, 709-716; Du et al. 2009 Reprod. Fertil. Dev. 21, 114). Activated embryos were in vitro-cultured in the well of the well (WOW) system, with 2 embryos per microwell, for 7 days in PZM-3 medium +0.3% BSA in the presence (FBS+) or absence (FBS-) of 10% FCS. Cleavage (Day 2, chi-square test) and blastocyst (Day 7, Fisher test) rates, on a per WOW basis, were compared for a level of significance of 5%. Our preliminary data indicate that the presence of serum in the IVC affected cleavage and blastocyst yield in a cell-type-dependent manner. The presence of serum enhanced the blastocyst yield for ADMSC, whereas for GC, only the absence of serum allowed any blastocyst development. The cell type and the pre-activation protocol did not appear to affect cleavage and embryo development to the blastocyst stage. Despite the low number of replications, our results reinforce the importance of optimizing the embryo production system taking into consideration the individual requirements for distinct cell types, procedures, and culture conditions. Table 1.Effects of cell type, pre-activation process and in vitro culture (IVC) medium on development of handmade pig cloned embryos

A practical method to determine the heating and cooling curves of x-ray tube assemblies

A practical method to determine the heating and cooling curves of x-ray tube assemblies with rotating anode x-ray tube is proposed. Available procedures to obtain these curves as described in the literature are performed during operation of the equipment, and the precision of the method depends on the knowledge of the total energy applied in the system. In the present work we describe procedures which use a calorimetric system and do not require the operation of the x-ray equipment. The method was applied successfully to a x-ray tube assembly that was under test in our laboratory.

Hydrochlorothiazide abolishes the anti-atherosclerotic effect of quinapril

1. Antihypertensive treatment has been demonstrated to result in persistent reductions in morbidity and mortality due to stroke. However, the coronary risk attributable to hypertension has been only partially reversed. We hypothesized that diuretics could have unfavourable effects on atherosclerosis. 2. New Zealand rabbits were fed a 0.5% cholesterol-enriched diet for 12 weeks, followed by a 0.1% cholesterol diet for another 12 weeks. During the last 12 week period, 40 animals were randomly assigned to one of four groups: (i) group I was the control group; (ii) group II received hydrochlorothiazide (10 mg/day); (iii) group III received quinapril (30 mg/day); and (iv) group IV was treated with hydrochlorothiazide (10 mg/day) plus quinapril (30 mg/day). 3. The treatments did not affect either the lipid profile or serum electrolytes and oxidative stress. However, endothelium-dependent vasorelaxation in isolated aortic rings was significantly improved with quinapril (group III) treatment (P < 0.001 vs other groups). In addition, therapy with quinapril promoted a significant reduction in atherosclerosis (intima area, intima/media ratio and perimeter of vessel with plaque; P < 0.05 vs other groups), as well as in cholesterol content of the aorta (P < 0.05 vs groups II and IV). 4. In conclusion, hydrochlorothiazide did not modify atherosclerosis and, when added to quinapril treatment, impaired the anti-atherosclerotic effect seen with quinapril alone.

[Assessment of cardiovascular reflexes in patients with mitral valve prolapse syndrome]

OBJECTIVE

Functional evaluation of Autonomic Nervous System in patients with Mitral Valve Prolapse Syndrome.

DESIGN

Study of cardiovascular reflexes.

SETTING

Out patients studied in the Laboratory for Study of Autonomic Nervous System Function of Santa Maria Hospital, Lisbon, Portugal.

MATERIAL AND METHODS

We studied 20 patients with clinical and echocardiographic diagnosis of mitral valve prolapse, who presented Mitral Valve Prolapse Syndrome, without significant mitral regurgitation, and with normal left ventricular function. Cardiovascular reflexes were analysed by mean of five tests.

RESULTS

In 75% of the cases, patients had results according to vagal hypofunction. Orthostatic hypotension was present in 40%. Among patients with orthostatic hypotension, 75% had postural phenomena. Among patients with postural phenomena, 75% had orthostatic hypotension.

CONCLUSIONS

In the present study, patients behaviour hasn't been uniform. Vagal hypofunction was present in 75% and orthostatic hypotension in 40% of the cases. A relation has been found between orthostatic hypotension and postural into.

Very-low dose antacid in treatment of duodenal ulcer. Comparison with cimetidine

Antacid (AA) in a very low dose (88 mmol/day) was compared to the standard 800-mg dose of cimetidine in healing duodenal ulcers. The influence of sex, age, symptom duration at entry, night pain, smoking, coffee consumption, and alcohol on ulcer healing was studied. The antacid was given in two different schedules: group I--20 ml 1 hr after breakfast and at bedtime; group II--10 ml 1 hr after breakfast and lunch and 20 ml at bedtime. Cimetidine (group III) was given in two divided doses: 400 mg 1 hr after breakfast and 400 mg at bedtime. Endoscopic control was performed after four weeks and, if necessary, after eight weeks of treatment. The healing rate after four weeks of treatment was, respectively, for groups I, II, and III, 45.5%, 55.8%, and 69.4% (group I = group II, and group III different from groups I and II). After eight weeks of treatment the healing rate was 61.5%, 80.8%, and 88.0% for groups I, II, and III, respectively (group II = group III, and group I different from groups II and III). Except for group I, smoking did not influence healing rate. Age, sex, symptoms at entry, night pain, and coffee consumption did not influence the treatment results. The authors concluded that the very low dose of magaldrate (88 mmol/day), when administered in three divided doses (10 ml after breakfast and lunch and 20 ml at bedtime) for eight weeks was as effective as 800 mg of cimetidine (400 mg twice a day) in healing duodenal ulcer.

[A sampling plan for evaluation of vaccinal coverage]

A sampling project applied in a survey for estimating the vaccination coverage in Araraquara County, S. Paulo State (Brazil), in 1983, is described. A target population of children aged 12-13 months was divided into the strata: children living in private dwellings (i.e. single-family houses) and those living in collective dwelling places (orphanage, asylum). R.H. Henderson and T. Sundaresan's method, proposed by the World Health Organization (WHO) for use by the Expanded Programme on Immunization (EPI) was applied to the first stratum. This method consists of the random selection of 30 partial areas with a degree of probability proportional to the respective partial populations in each area chosen; a starting point ("household") is selected at random within each selected area; the selection of 7 children within each area begins with the first household and continues according to fixed rules. The sample of the first stratum was taken from areas in both urban and rural zones. In the urban zone, after the selection of the area and before the selection of the starting point, an intermediate stage, which consist in the selection of a block with probability proportional to its estimated population, was introduced. A sample was selected form the second stratum with the same sampling fraction used in the first stratum. The ratio-estimate is proposed as the estimator of the vaccination coverage rate and the formula for the calculation of the standard error is presented.

[Sampling methods for the estimation of vaccination coverage]

Apresentam-se sucintamente dois métodos de amostragem que visam a seleção de uma amostra de crianças de fixada faixa de idade, residentes em determinada área geográfica de interesse, para estimação de cobertura vacinal: o método de R.H. Henderson e T. Sundaresan, o método do Departamento de Epidemiologia e de Métodos Quantitativos em Saúde da Escola Nacional de Saúde Pública. Um terceiro método de amostragem é proposto. O primeiro método apresentado (Henderson e Sundaresan) é empregado no Programa Ampliado de Imunização e nesse programa é considerado eficiente, simples e não dispendioso. O segundo e o novo método, que apresentam modificações do primeiro, constituindo alternativas deste, visam diminuir o erro quadrático médio nas estimativas, conquanto sejam menos simples e mais dispendiosos que aquele. Visto que, na estimação da cobertura vacinal, o estimador empregado pressupõe amostra autoponderada, a preocupação maior do método aqui proposto foi a de proporcionar uma amostragem segundo a qual se tenha equiprobabilidade de seleção para qualquer criança do grupo etário estudado residente na área de interesse, independentemente de qualquer condição.