A progesterona desempenha uma função de extrema importância para o desenvolvimento embrionário inicial, por meio da regulação do ambiente uterino no período prévio à adesão dos embriões ao endométrio. Nesse contexto o objetivo do presente estudo foi avaliar os efeitos da suplementação com progesterona ou progestágeno durante a fase inicial da gestação sobre o ambiente uterino e desenvolvimento embrionário de suínos, bem como seus efeitos no desempenho da leitegada nascida. Foram realizados dois experimentos. No experimento 1 utilizou-se 40 porcas e 28 marrãs que no 6º dia de gestação foram distribuídas em um dos três grupos experimentais: fêmeas suplementadas com 20 mg de altrenogest (Regumate®) do 6º ao 12º dia de gestação (RU; n = 23); fêmeas suplementadas com 2,15 mg/kg de progesterona de longa ação (Sincrogest®), injeção única no 6º dia de gestação (PG; n = 24); fêmeas não suplementadas (CON; n = 21). Esse experimento foi delineado de maneira inteiramente casualizada em um arranjo fatorial, sendo que a categoria (marrã ou porca) foi considerada fator 1 e os grupos (CON, RU e PG) fator 2. 18 fêmeas foram eutanasiadas no 13º dia de gestação, e 50 fêmeas no 28º dia de gestação. Foram analisados: taxa de prenhez, taxa de ovulação, sobrevivência embrionária, tamanho e peso de embriões e útero, volume e peso de corpos lúteos, volume das vesículas embrionárias, dosagem sérica de progesterona e 17β- estradiol, morfometrias glandular e de epitélio luminal do uterino. No experimento 2 foram utilizadas 75 matrizes, que no 6º dia de gestação foram alocadas de maneira interiramente casualisada em um dois grupos: fêmeas suplementadas com 20 mg de altrenogest (Matrix®) do 6º ao 12º dia de gestação (ALT; n = 36); fêmeas não suplementadas (CTR; n = 36). Analisadas: taxa de prenhez, período gestacional, peso médio e homogeneidade da leitegada, número de leitões mumificados, natimortos e nascidos vivos, quantidade de leitões nascidos com menos de 800 gramas. Não houve influência dos tratamentos sobre a taxa de prenhez e a sobrevivência embrionária foi prejudicada apenas para marrãs do grupo RU. Para o desenvolvimento embrionário os resultados divergiram entre as categorias, as marrãs do grupo CON apresentaram embriões maiores e mais pesados quando comparados aos grupos suplementados, bem como vesículas embrionárias maiores. Para as porcas o grupo RU apresentou embriões maiores e mais pesados. De maneira geral as suplementações com progesterona ou progestágeno estimularam o crescimento do epitélio glandular aos 13 dias de gestação, mas não tiveram efeito sobre epitélio luminal. Já aos 28 dias de gestação o efeito da estimulação foi apenas observado para marrãs do grupo PG. Os tratamentos estimularam também o crescimento dos corpos lúteos que foram maiores e mais pesados para os grupos suplementados. Em relação ao desempenho da leitegada, analisado no experimento 2, não houve efeito de tratamento para nenhuma das variáveis analisadas. A suplementação de progesterona/progestágeno a partir do 6º dia de gestação estimulou o crescimento do epitélio glandular uterino e afetou o desenvolvimento embrionário inicial, mas não exerceu efeito significativo sobre o desempenho da leitegada. / Progesterone plays a role of extreme importance for early embryonic development by regulating the uterine environment in the period prior to the adhesion of the embryos to the endometrium. In this context, the objective of the present study was to evaluate the effects of progesterone or progestogen supplementation during early gestation on the uterine environment and embryo development of pigs, as well as their effects on litter performance. Two experiments were carried out. In the experiment 1, 40 sows and 28 gilts were used, which were distributed in one of the three experimental groups: females supplemented with 20 mg altrenogest (Regumate®) from the 6th to the 12thh day of gestation (RU; n = 23); females supplemented with 2.15 mg / kg long acting progesterone (Sincrogest®), single injection at 6th day of gestation (PG; n = 24); females not supplemented (CON; n = 21). This experiment was completely randomized in a factorial arrangement, with the category (gilt or sow) being considered as factor 1 and the groups (CON, RU and PG) factor 2. 18 females were euthanized on the 13th day of gestation, and 50 females on the 28th day of gestation. Pregnancy rate, ovulation rate, embryo survival, embryo and uterus size and weight, volume and weight of corpora lutea, volume of embryonic vesicles, serum progesterone and 17β-estradiol concentrations, morphometric of uterine glandular epithelium and uterine luminal epithelium. In the experiment 2, 75 sows were used, which at the 6th day of gestation were allocated in a randomized manner in one of two groups: females supplemented with 20 mg of altrenogest (Matrix®) from 6 to 12 days of gestation (ALT; = 36); females not supplemented (CTR; n = 36). The variables analyzed were: pregnancy rate, gestation length, average of litter weight, within-litter variation, number of mummified, stillborn and live born piglets, number of piglets born with less than 800 grams. There was no influence of treatments on the pregnancy rate and embryo survival was impaired only for gilts in the RU group. For embryonic development the results differed among the categories, the gilts of the CON group had larger and heavier embryos when compared to the supplemented groups, as well as larger embryonic vesicles. For the sows the RU group presented larger and heavier embryos. In general, progesterone or progestogen supplementation stimulated the growth of the glandular epithelium at 13 days of gestation, but had no effect on luminal epithelium. However, on day 28 of gestation the stimulatory effect was only observed for gilts of the PG group. Treatments also stimulated the growth of corpora lutea that were larger and heavier for the supplemented groups (RU and PG). Regarding the performance of the litter, analyzed in experiment 2, there was no treatment effect for any of the variables analyzed. In conclusion, Progesterone / progestogen supplementation from day 6 of gestation affected the uterine glandular epithelium area, and early embryonic development, but did not have a significant effect on the litter performance.

The aim of this final diploma thesis is to evaluate the production specific emission of greenhouse and load gases from selected pig breeding located in Hodětín near Bechyně, South Bohemian Region. The work focuses on the breeding hall, where the pregnant sows and the nursing sows including piglets are located separately. A total of 6 measurements were carried out, which are further compared with each other and with the latest edition of the reference document BREF. The thesis answers the questions and the selected farm is evaluated according to the principles of "Good Agricultural Practice" according to the available BAT techniques listed in the BREF reference document. The season plays a role in assessing and evaluating individual measurements. In winter, ammonia concentration is higher due to less frequent ventilation, causing low temperature and high humidity in the breeding hall. These two basic aspects are described and it is explained why this is the case and why workers approach this solution to the situation. In conclusion, there are methods and recommendations to contribute to lower emissions in selected pig breeding.

Orientador: Maria Cristina Thomaz / Banca: Otto Mack Junqueira / Banca: Jacinta Diva Ferrugem Gomes / Resumo: Foram conduzidos dois ensaios para avaliar a utilização de polpa cítrica, com ou sem a adição do complexo enzimático, nas dietas de suínos nas fases de crescimento e terminação. 0 primeiro ensaio teve o objetivo de determinar os coeficientes de digestibilidade da polpa cítrica e foram utilizados 16 suínos, com peso inicial de 30,42 ± 2,44kg, os quais foram alojados em gaiolas de estudos metabólicos. Por apresentar 1677 kcal de EM/kg, 23,09% de FDN e 18,47% de FDA, a polpa cítrica mostrou-se um ingrediente viável de ser utilizado nas rações de suínos. No segundo ensaio, foram utilizados 72 suínos, com peso inicial de 25,71 ± 7,51 kg e final de 98,81 ± 10,64kg, que receberam rações contendo diferentes níveis de polpa cítrica (0, 5, 10 e 15%), com ou sem a adição do complexo enzimático, sendo avaliados quanto ao desempenho, digestibilidade das dietas, características das carcaças e avaliação econômica do uso das dietas. Conclui-se que a inclusão de até 15% de polpa cítrica com ou sem a adição do complexo enzimático nas dietas para suínos, dos 70 aos 130 dias de idade, diminui o CDR e melhora a CA, porém, os animais apresentam respostas adaptativas no período total do experimento, não sendo observadas diferenças no desempenho. A digestibilidade dos nutrientes não é modificada, na ausência do complexo enzimático, sendo que na presença do produto, há melhora na digestibilidade de todos os nutrientes. As caracteristicas de carcaça não são influenciadas pelos níveis de polpa cítrica, exceto o rendimento de carcaça, que diminui linearmente. A relação gordura/carne também diminui linearmente, a medida em que aumentam os níveis de polpa cítrica, na ausência do complexo enzimático. Na presença do produto, a relação gordura/carne, apresenta... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Two experiments were conducted to evaluate the use of citrus pulp, with or without the addition of an enzyme complex, in the diets growing and finishing pigs. The first trial was to determine the digestibility coefficients of citrus pulp and 16 pigs were used, with initial weight of 30.42 ± 2.44 kg, which were housed in cages for metabolic studies. To present 1677 kcal / kg, 23.09% neutral detergent fiber and 18.47% acid detergent fiber, the citrus pulp was a viable ingredient to be used in the feed for pigs. In the second trial, 72 barrows, were used with initial weight of 25.71 ± 7.51 kg and final weight of 98.81 ± 10.64kg, which received diets containing different levels of citrus pulp (0, 5, 10 and 15%), with or without the addition of an enzyme complex, and were assessed for performance, digestibility of diets, carcass characteristics and economic evaluation about the use of diets. Conclude that inclusion of up to 15% of citrus pulp with or without the addition of the enzyme complex in diets for pigs from 70 to 130 days of age, decrease the CDR, and improves the CA, however, the animals showed adaptive responses in the total experiment, no differences being observed in performance, being what the digestibility of nutrients was not modified in the absence of the enzyme complex. In the presence of the product, there is improvement in the digestibility of all nutrients. The carcass characteristics are not influenced by levels of citrus pulp, except the carcass yield, which decreases linearly. The fat/meat relationship also decreases linearly, as they increase the levels of citrus pulp in the absence of the enzyme complex. In the presence of the product the fat/meat relationship has a quadratic behaviour and the level of 7.78% citrus pulp, provides the better relation. The use of... (Complete abstract click electronic access below) / Mestre

O Brasil ocupa uma posição de destaque mundial em relação à produção agropecuária, sendo necessário fornecer segurança microbiológica aos consumidores. Salmonella é um agente causador de infecções alimentares em seres humanos, de forma que os produtos de origem suína são responsáveis por cerca de 5-10% dos surtos em humanos. O controle depende do conhecimento da distribuição da bactéria desde o rebanho até o frigorífico. Em regiões com altas prevalências no campo, esforços direcionados primeiramente em reduzir a prevalência nos rebanhos visam minimizar os riscos de contaminação dos produtos. Neste sentido, medidas de biossegurança, seguindo boas práticas de produção agropecuária, são fundamentais. Além disso, a aplicação de intervenções complementares são, possivelmente, formas de reduzir a prevalência em um período de tempo mais curto. Desta forma o objetivo deste trabalho foi validar três estratégias: 1) utilização de um prebiótico Actigen®™ na ração dos animais, (PRE); 2) uma vacina viva Enterisol SC 54®, (VAC) e 3) o sistema de wean-to-finish, (WTF). Estes grupos foram comparados entre si e com o sistema tradicional em três sítios, o grupo controle (GC), frente à soroprevalência e contaminação em carcaças. Cada estratégia foi realizada em três repetições, sendo colhidas amostras de sangue de 55 animais de cada lote no dia do alojamento na terminação e quatro dias antes do abate. Suabe de 40 carcaças de cada lote foram colhidas antes do resfriamento. As soroprevalências e frequências de isolamento foram comparadas entre os grupos por meio de teste de qui-quadrado. A soroprevalência pré-abate foi estatisticamente menor no grupo PRE 50,3% em relação ao WTF, VAC e GC, com 99%, 96,9% e 98,8% respectivamente. As frequências de isolamentos em superfície de carcaça variaram de 0% a 29,1% nos grupos PRE e VAC respectivamente, sendo que ambas diferem significativamente entre si e dos grupos CG 18,33% e WTF 15% (p<0,05). Pode-se comprovar a eficácia do prebiótico em prevenir a infecção a campo frente às demais estratégias. Em relação às contaminações de carcaças, os resultados corroboram com os conhecimentos acerca do papel da pressão de infecção do campo nas contaminações na planta frigorífica. / Brazil has been increasing its worldwide position in relation to agricultural production, and is necessary providing food safety to consumers. Salmonella is a foodborne pathogen for humans and pork products play an important role in the amount of outbreaks. The control depends on the knowledge of the distribution of the bacteria occurrence from the herd to the slaughterhouse. In regions with high on farm prevalence, efforts are primarily directed to reduce the prevalence in the swine population in order to minimize the risks of products contamination. In this sense, biosecurity measures and good production practices are useful. Moreover, increase the knowledge about additional interventions, to reduce on farms prevalence in a shorter period of time, also is important. Therefore, the objective of this work was to validate three strategies: 1) use of Actigen ® ™ prebiotic in animal feed, (PRE); 2) a live vaccine Enterisol SC54® (VAC); and 3) the system of wean- to-finish, (WTF). Seroprevalence and contamination on carcasses surface in these groups were compared with the traditional system in three sites (the control group-CG). Each strategy was performed in three replicates, and blood samples were collected from 55 animals of each batch at the first day of finishing phase and four days before slaughter. Swabs of 40 carcasses were taken from each batch before chilling. The seroprevalence and isolation frequencies were compared between groups using logistic regression. The seroprevalence before slaughter was lower in PRE (50.3%) compared with the WTF, VAC and GC groups, with 99%, 96.9% and 98.79%, respectively. The frequency of Salmonella isolation was lower in PRE group 0%, when compared with the other groups (p<0.05). The results prove that prebiotic is able to prevent infection in the field compared to the other strategies. Regarding the carcass contamination, these finds are consistent with the knowledge on the role of infection pressure in the field contamination in the plant.

The purpose of this study was to determine differences between littermate boars and barrows for performance and carcass traits in the Iowa and Northeast Iowa Swine Testing Stations. Data were obtained from 917 litters including 1,804 boars and 917 barrows. The data included 1,086 boars and 581 barrows from the Iowa Station at Ames, Iowa, and 718 boars and 336 barrows from the Northeast Iowa Station at New Hampton, Iowa. The Iowa Station data were obtained over a period of 12 seasons from the fall of 1979 through the fall of 1985, and the data from the Northeast Iowa Station were collected in eight seasons from the fall of 1981 through the spring of 1985. The spring testing season included pigs born from November through March, and the fall testing season included pigs born from May through September. Littermate boars and barrows from the following purebred breeds were used: Berkshire, Chester White, Duroc, Hampshire, Landrace, Poland China, Spotted, and Yorkshire. Boars grew .03 (2.21+/-.20 vs. 2.18+/-.21) and .10 (2.21+/-.18 vs. 2.11+/-.22) pounds/day faster (P<.01) than littermate barrows in the Iowa and Northeast Iowa Stations. Boars had .58 (.80+/-.08 vs. 1.38+/-.20) inches less (P<.01) backfat than littermate barrows (N=581) in the Iowa Station. In the Northeast Iowa Station, boars were significantly (P<.01) leaner than barrows when comparing average backfat of boars with carcass backfat measurements of Ilttermate barrows at the tenth rib (.76+/-.06 vs. 1.06+/-.21) or the average of three carcass backfat measurements (.75+/-.08 vs. 1.29+/-.18 and .79+/-.05 vs. 1.31+/-.19). Boars had .67 (5.49+/-.42 vs. 4.82+/-.67) and .66 (5.62+/-.28 vs. 4.96+/-.65) square inches larger (P<.01) loin eye areas than littermate barrows in the Iowa and Northeast Iowa Stations, respectively. The t test revealed no significant (P>.05) differences between boars and barrows for average daily gain among the eight major breeds in the Iowa Station. However, at the Northeast Iowa Station, the Duroc (2.39+/-.19 vs. 2.12+/-.21) and Hampshire (2.16+/-.17 vs. 2.07+/-.24) boars grew significantly faster (P<.01) than littermate barrows. The t test also revealed that boars averaged seven days (156.00+/-10.78 vs. 163.00+/-12.90) younger (P<.01) at 230 pounds than barrows in the Northeast Iowa Station. Although the sample size was small and the differences nonsignificant, there were some breeds in which barrows appeared to grow faster than boars. The I test for boar-barrow differences among breeds revealed that boars had significantly (P<.01) less average backfat than littermate barrows for eight major breeds in the Iowa Station and for seven breeds in the Northeast Iowa Station. For both stations, the differences in backfat thickness between boars and barrows was lowest for the Hampshire breed and the greatest differences were between boars and barrows in the Chester White, Yorkshire, Berkshire and Landrace breeds. The t test for loin eye area revealed that boars had significantly (P<.01 or .05) greater loin eye area than barrows for all breeds except Poland China in the Iowa Station and Landrace in the Northeast Iowa Station. The sex differences between littermate boars and barrows for backfat and loin eye area were significantly different (P<.01) for all years and seasons in the Iowa and Northeast Iowa Stations. The sex differences between littermate boars and barrows for backfat and loin eye area have been increasing in both stations with the largest increase occurring during the last five years. The differences between boars and barrows for days to 230 pounds were significantly different (P<.01) In all years and seasons for both stations. In comparing data for 1981 and 1985, both boars and barrows averaged ten days younger at 230 pounds In 1985 than in 1981. Coefficients of correlation for various measurements of performance and carcass cutability between littermate boars and barrows were determined. In general, there were positive associations between boar and barrow data; however, the correlations were relatively low. The predictive value of the barrow data appears to be of little use In estimating breeding values for boars. Although a limited number of Chester White pens were included in this study, the coefficients of correlation between littermate boars and barrows suggest that castration may have a different effect upon performance and carcass cutability of Chester White than for other breeds. Unfortunately for Chester White breeders, there appears to be a much higher positive correlation between average daily gain and beckfat thickness for Chester White boars and barrows than for other breeds. In other breeds, the correlation between growth rate and backfat is low enough to allow simultaneous progress for improving both traits. A similar desirable low correlation was found between growth rate and loin eye area for other breeds. The coefficients of correlation between backfat and loin eye area were greater for barrows than boars, suggesting that errors of measurement may have been prevalent in the boar data. Large errors In measurement of boar backfat could account for some or all of the increased difference in backfat thickness observed between littermate boars and barrows during recent years.

Two experiments were used to evaluate the potential interaction of fat source and vitamin E (VE) in heavy slaughter weight pigs. In Experiment 1, a total of 64 individually-fed pigs (28.41 ± 0.83 kg) were randomly assigned to 8 dietary treatments in a 4×2 factorial arrangement. Fat treatments included cornstarch (CS), tallow (TW), corn-oil (CO), and coconut-oil (CN). VE treatments were dietary α-tocopheryl acetate (ATA) at 11 and 200 ppm. In Experiment 2, a total of 72 individually fed pigs (28.55 ± 1.16 kg) were randomly assigned to 12 dietary treatments in a 2 × 6 factorial arrangement. Fat treatments were TW and CO. VE treatments included four levels of ATA (11, 40, 100, and 200 ppm) and two levels of mixed tocopherols (primarily γ-tocopherol; 40 and 100 ppm). VE deposition, growth performance, and meat quality were measured in both experiments. In both experiments, interaction between fat sources and VE were detected (P < 0.01) on plasma VE concentration, which increased (P < 0.01) with time and with increasing dietary VE, but increased faster (P < 0.05) in pigs fed with CN and TW compared to pigs fed CS and CO. Compared to CO, more saturated dietary fat sources (CN and TW) led to firmer belly (P < 0.01), which had more (P < 0.01) SFA and MUFA while less (P < 0.05) Feed/Gain in Phase 4 and Phase 5. In Experiment 2, increasing dietary ATA increased overall ADG (linear, P = 0.02), with an interaction (P < 0.05) with fat sources on cumulative ADG during Phase 1-4, wherein pigs fed CO, but not TW, had increased ADG with increasing dietary ATA. Increasing dietary ATA increased (quadratic, P < 0.05) liver SOD activity, and decreased (quadratic, P < 0.05) liver MDA content. The oxidative stability of loin was improved (P < 0.01) when dietary ATA increased over 40 ppm. In summary, both dietary fat source and VE supplementation affected the response measures.

Thesis (M.A. (Agricultural Management)) -- University of Limpopo, 2013 / A study was conducted to determine environmental and socio-economic factors affecting pig productivity in communal areas. A questionnaire was administered to collect data on production environment and socio-economic variables underlying productivity in Sekhukhune District. Production environment included explanatory sex of the piglet, season of birth, feed type, housing type, municipality, herd size, health management and disease prevalence, while socio-economic variables included household size and gender of head of household, age, level of education and employment status. A total of 112 farmers were interviewed from 25 villages. Data on productivity were collected using production record sheets. Performance parameters in the production sheets included litter size, litter weight, individual birth weight, live weight and mortality. Monitoring was done from birth date to subsequent farrowing date at the farmers’ backyard. One farrowing sow per producer was used and a total of 605 piglets were monitored in the municipalities. A total of 1468 indigenous pigs were kept for breeding with 104 castrated males occupying less space in the production system within the district. Feeding was characterized by kitchen wastes or garbage at total of 78 farmers, 22 feeding garbage and grains, and only 12 farmers feeding concentrate. There was measles prevalence in the production system with a total of 41 farmers treating the suspected pigs; the larger number (71) however, did not treat pigs. Health did not affect (P>0.05) litter size and birth weight. Birth weight was affected (P>0.05) by disease prevalence, herd size, household head sex, age and education, and family size. Mean litter size was 4.38 piglets at birth, mean litter weights of 5.78 kg, mean birth weight of 1.32, and mean mortality at 2.31 piglets. Season, feed, municipality, diseases, herd size, the age, education and employment of household head affected pre-weaning mortality (P<0.05). v There is statistical evidence (P<0.05) that there were associations between litter size, litter weight, birth weight and mortality and the feed, municipality, diseases, herd size, the age, education and employment of household head respectively. There were deficiencies in the entire production system with regards to pig management practices, feeding practices, housing of pigs, breeding systems, herd composition and size and the general practices in the keeping of the pig herds by majority of pig producers. These deficiencies call for introduction of sound pig management plans in communal areas which should include keeping pigs indoor to account for the healthy herd, proper feeding and sound breeding plans.

Graduation date: 1994

Thesis (Ph. D.)--University of Nevada, Reno, 2005. / "December, 2005." Includes bibliographical references (leaves 194-212). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm.

The effects of conjugated linoleic acid (CLA) on lipogenesis and preadipocyte proliferation in young pigs were evaluated in two separate experiments. The first compared dietary effects of linoleic acid, beef tallow, and CLA on composition, lipogenesis, and DNA synthesis. Eighteen pigs weaned at 17 d of age were allotted randomly to corn-based diets supplemented with 1.5% corn oil, 1.5% tallow, or 1.5% CLA. The second experiment evaluated the effects of CLA included with diets high in polyunsaturated fat or beef tallow. Twenty-four pigs weaned at 17 d of age were allotted randomly to one of four corn-based diets supplemented with: 15% corn oil, 12% corn oil + 3% CLA, 15% tallow, and 12% tallow + 3% CLA. The piglets in both trials were fed a basal diet for 7 d and their respective diet for 35 d. [U-14C]Glucose incorporation into total lipids was (experiment 1): 10.64, 11.04, 13.64; (experiment 2): 21.15, 17.54, 21.34, and 19.52 nmol/(105 cells per h) for subcutaneous (s.c.) adipose tissue from corn oil, tallow, CLA; corn oil, corn oil + CLA, tallow, and tallow + CLA-fed piglets, respectively. Tritiated thymidine incorporation into DNA was not different in s.c. adipocytes across treatment groups, but was 5,581, 2,794, 6,573, and 3,760 dpm/(105 cells per h) in s.c. stromal vascular cells from corn oil, corn oil + CLA, tallow, and tallow + CLA-fed piglets, respectively (CLA main effect p<0.034). Additionally, there was a greater proportion of s.c. adipocytes in the smaller, 180-pL cell fraction from the corn oil + CLA-fed pigs (p<0.0074). CLA in the diet increased the s.c. adipose tissue concentration of 18:0 and decreased 16:1 and 18:1 (p<0.05), suggesting depression of stearoyl-coenzyme A desaturase (SCD) enzyme activity in the CLA-fed pigs. The concentration of CLA isomers was raised only slightly in s.c. adipose tissue with the addition of CLA to the diets even though the CLA oil contained 62% CLA isomers. No effects on the growth of young pigs were observed. However, CLA caused a more saturated fatty acid composition and may suppress preadipocyte proliferation, apparent SCD activity, and lipid filling of smaller cells.