Estimates of genetic homeostasis in maize

Genetic homeostasis was studied in different maize (Zea mays L.) genotypes and populations to determine whether selection has affected homeostasis and to determine whether homeostasis is heritable. The maize materials included one group of six inbred lines released before the 1960s (older lines), and another group of six inbred lines released after the 1970s (newer lines). Within each group, single cross, F2, and backcross generations were developed. The experiments were conducted at two Iowa locations in 1985 and 1986. Individual plant measurements were taken for eight maize traits: yield, ear length, ear diameter, kernel-row number, kernel depth, plant and ear height, and number of tassel branches. The objectives of this study were to compare genetic homeostasis of the older versus the newer maize lines to determine whether selection of newer lines has changed the levels homeostasis and to study whether the homeostatic effects are transmitted from the inbred lines to their single cross, FI, and backcross generations;Estimates of genetic homeostasis were obtained using the proportion of the environmental variance contained in the within-plot variance. The significance and magnitude of the genotype x environment interaction mean squares and the coefficient of variation were also used as preliminary estimates of homeostasis. The coefficient of variation, however, was not a good estimator because it had a negative and highly significant correlation with the mean. Genetic homeostasis depended on the level of heterogeneity and heterozygosity of the maize genotypes and populations. The homogeneous and homozygous inbred lines were the least homeostatic. The homogeneous and heterozygous single crosses exhibited good homeostasis. The F2 and backcross generations (heterogeneous and 50% heterozygous) expressed similar homeostasis among them, and better homeostasis than the single crosses;The newer lines were more homeostatic than the older lines. The inbred lines were consistent in transmitting in a heritable manner the homeostatic effects, either good or bad, to their single cross, F2, and backcross generations. In most instances, the eight traits measured followed the same tendency in all comparisons among generations within both groups. Kernel depth, however, did not have a regular pattern of transmission of the homeostatic effects across generations

Genetic relationships of the Yucatan black hairless pig with Iberian breeds using single nucleotide polymorfisms

Para realizar programas de conservação ex-situ de suínos crioulos, é importante determinar quais animais serão criados, preferencialmente aqueles com maior componente de genética ibérica, para preservar sua origem. Uma subpopulação de porco preto calvo de Yucatán (YBHP) foi usada para estimar sua diversidade genética e estrutura populacional. Um total de 104 suínos adultos foram selecionados levando-se em consideração características como ausência de pelos, pele preta (sem manchas), casco preto e focinho reto. O painel GGP-50K foi utilizado para a genotipagem dos SNPs em animais YBHP, e informações de porcos sem pelos ibéricos e de Yucatán dos Estados Unidos (USYU) foram retiradas de bancos de dados. Todas as análises foram realizadas com o software PLINK v1.9 e v2.1. Os valores dos índices de endogamia e fixação foram menores em YBHP, com altos valores de índice de heterozigosidade e alogamia observados, que concordam com os obtidos nas populações de Canárias e Chato Murciano. De acordo com os clusters gerados pela análise “GenomaWide Identity By State”, quatro grupos foram identificados, um dos quais incluiu porcos de Guadyerbas, USYU e YBHP. Entre as populações, YBHP estava intimamente relacionado com os porcos sem pelo de Guadyerbas, USYU e Canárias. A análise de componentes principais mostrou o mesmo resultado. De acordo com os resultados obtidos nas corridas de investigação de homozigose, visando obter consenso de pools de regiões de sobreposição, foram identificados 119 SNPs associados a genes e processos biológicos. Os genes BMP7 e NSUN2 foram associados à diferenciação de células epiteliais, morfogênese e desenvolvimento epitelial. Para metabolismo de nutrientes: energia, os genes HADHA, PPARA, ADD1/ SREBF1 e FAT1 foram identificados.  To conduct ex-situ creole pig conservation programs, it is essential to determine which breeding animals will be used, preferentially those with a more significant Iberian genetic component to preserve their origin. This study used a Yucatan black hairless pigs (YBHP) subpopulation to estimate its genetic diversity and population structure. One hundred four adult pigs were selected for the absence of hair, black skin (without spots), black hoof, and straight snout. The porcine-GGP-50K chip was used for SNP genotyping in YBHP, and information on Iberian and Yucatán hairless pigs from the United States (USYU) was taken from databases. All analysis was performed using PLINK v1.9 and v2.1 software. Inbreeding and fixation index values were lower in YBHP, with high observed heterozygosity and allogamy index values, which agree with those obtained in the populations of Canarias and Chato Murciano. According to the clusters generated by the “Genome-Wide Identity by State” analysis, four groups were identified, one of which included pigs from Guadyerbas, USYU, and YBHP. Between populations, YBHP was closely related to the hairless pigs from Guadyerbas, USYU, and Canarias. Principal component analysis showed the same result. According to the results obtained from the runs of homozygosity investigation, aimed to get pools consensus of regions of overlapping, 119 SNPs associated with genes and biological processes were identified. The BMP7 and NSUN2 genes were associated with epithelial cell differentiation, morphogenesis, and epithelial development. For nutrient metabolism: energy, the HADHA, PPARA, ADD1/SREBF1, and FAT1genes were identified

Učinak praha avokada, suncokretova ulja te različitih omjera voluminozne i koncentrirane krme u obroku na unos hrane, probavljivost hrane i proizvodnost mladih ovnova

The objective of this study was to evaluate the inclusion of avocado flour and sunflower oil as energy sources in different proportions, as well as different forage:concentrate ratios on the productive performance and feed intake of male rams, and the in vitro dry matter digestibility, organic matter digestibility and gas production. The intake was measured in diets containing avocado flour or sunflower oil with 60% forage: 40% concentrate, and in diets with different forage:concentrate ratios and 10% inclusion of avocado flour or sunflower oil. The daily weight gain was registered for 84 days, the in vitro dry matter digestibility was determined at 48 h, and the in vitro gas production was evaluated at 72 h. The partial production of gas at 24 hours, raw protein, raw fat, and ash were used to estimate the metabolizable energy and organic matter digestibility. Low levels of avocado flour and sunflower oil in the diet showed the highest intake, in vitro dry matter digestibility and in vitro gas production. Daily weight gains were 0.28 kg in avocado flour and 0.30 kg in sunflower oil diets, both at 10% inclusion and 40% forage: 60% concentrate. The inclusion of high levels of avocado flour or forage in the diet decreased the feed intake of male sheep. The best avocado flour level was 10% with 40% forage: 60% concentrate.Cilj rada bio je istražiti utjecaj različitih omjera između praha avokada i suncokretova ulja kao izvora energije, te različitih omjera između voluminozne i koncentrirane krme u obroku na unos hrane i proizvodnost mladih ovnova. Osim toga, in vitro istražena je probavljivost suhe tvari, probavljivost organske tvari i proizvodnja plina. Unos hrane mjeren je u obrocima koji su sadržavali prah avokada ili suncokretovo ulje uz omjer između voluminozne i koncentrirane krme od 60:40% ili u obrocima sa različitim omjerom voluminozne i koncentrirane krme uz dodatak 10% praha avokada ili suncokretova ulja. Dnevni prirast bilježen je tijekom 84 dana. Probavljivost suhe tvari in vitro određivana je 48 h, a proizvodnja plina in vitro 72 h od uzimanja uzoraka. Za određivanje metaboličke energije i probavljivosti organske tvari korišteni su parcijalna proizvodnja plina 24-ti sat, sirovi protein, sirova mast i pepeo. Niske razine praha avokada i suncokretova ulja u obroku rezultirale su najvišim unosom hrane te najvišom in vitro probavljivošću suhe tvari i in vitro proizvodnjom plina. Dnevni prirast bio je 0,28 kg u životinja kojima je davano 10% praha avokada, 0,30 kg u životinja kojima je davano 10% suncokretova ulja, pri čemu je omjer voluminozne i koncentrirane krme iznosio 40:60%. Dodavanje visokih razina praha avokada ili voluminozne krme u obrok dovelo je do nižeg unosa hrane kod mladih ovnova pa je zaključeno da je najpovoljnija razina dodanog praha avokada 10% uz omjer voluminozne i koncentrirane krme 40:60%

Estimates of genetic homeostasis in maize

Genetic homeostasis was studied in different maize (Zea mays L.) genotypes and populations to determine whether selection has affected homeostasis and to determine whether homeostasis is heritable. The maize materials included one group of six inbred lines released before the 1960s (older lines), and another group of six inbred lines released after the 1970s (newer lines). Within each group, single cross, F2, and backcross generations were developed. The experiments were conducted at two Iowa locations in 1985 and 1986. Individual plant measurements were taken for eight maize traits: yield, ear length, ear diameter, kernel-row number, kernel depth, plant and ear height, and number of tassel branches. The objectives of this study were to compare genetic homeostasis of the older versus the newer maize lines to determine whether selection of newer lines has changed the levels homeostasis and to study whether the homeostatic effects are transmitted from the inbred lines to their single cross, FI, and backcross generations;Estimates of genetic homeostasis were obtained using the proportion of the environmental variance contained in the within-plot variance. The significance and magnitude of the genotype x environment interaction mean squares and the coefficient of variation were also used as preliminary estimates of homeostasis. The coefficient of variation, however, was not a good estimator because it had a negative and highly significant correlation with the mean. Genetic homeostasis depended on the level of heterogeneity and heterozygosity of the maize genotypes and populations. The homogeneous and homozygous inbred lines were the least homeostatic. The homogeneous and heterozygous single crosses exhibited good homeostasis. The F2 and backcross generations (heterogeneous and 50% heterozygous) expressed similar homeostasis among them, and better homeostasis than the single crosses;The newer lines were more homeostatic than the older lines. The inbred lines were consistent in transmitting in a heritable manner the homeostatic effects, either good or bad, to their single cross, F2, and backcross generations. In most instances, the eight traits measured followed the same tendency in all comparisons among generations within both groups. Kernel depth, however, did not have a regular pattern of transmission of the homeostatic effects across generations.</p

Selección de progenitores de maíz para la obtención de semilla híbrida por pequeños agricultores

The seed of actual high yielding hybrids are very expensive and local farmers tend to use advanced generations to reduce costs. Abetter choice is to produce seed of maize intervarietal hybrids. The objective of this research was to describe the experience of a group of maize producers in the seed production, utilization and improvement of their parents of intervarietal hybrids. The study was conducted in Nayarit State, Mexico. In 1996, a group farmers, supported by a technical researcher, evaluated two maize intervarietal crosses. The cross B840xC343 yielded better than nine commercial hybrids. This motived the farmers to produce 20 tons of seed in eight intervarietal crosses during the winter season of 1997/98. The cost of the seed production was 50% less than the cost of commercial hybrid seed. The eight intervarietal crosses were commercial planted in about 400 hectars and were evaluated in four experiments by the farmers. The results showed that two crosses, P3028xA7573 and C385xD880, had the best results. The first cross had a heterosis of 4.1% over the high yielding parent and the second a heterosis of 30% over a parent. Since 1999, the parents of the best intervarietal cross is being improved by reciprocal recurrent selection of half siblings, two years per cycle.El costo creciente de semilla híbrida de maíz ha limitado la productividad del cultivo en México. Por eso, los agricultores tienden a sembrar híbridos de segunda generación para reducir costos. Una mejor opción es utilizar el modelo Productor-Experimentador en la decisión de sembrar semilla de cruzas intervarietales. El objetivo del estudio fue describir la experiencia que ha tenido un grupo de productores de Santa María del Oro, Nayarit, en la producción, utilización y mejoramiento de cruzas intervarietales de maíz. En 1996, los productores sembraron seis experimentos donde observaron que la cruza B840xC343 rindió mejor que nueve híbridos comerciales. Con esta motivación, en 1997/98, los agricultores produjeron 20 toneladas de semilla de ocho cruzas. Los rendimientos de semilla fueron de 2 a 3 t/ha, así la semilla fue distribuida en la comunidad a menos del 50% del costo del híbrido comercial. En 1998, se sembraron alrededor de 400 ha con su semilla producida y se evaluaron las ocho cruzas, en cuatro experimentos. Los resultados mostraron que las mejores cruzas fueron P3028xA7573 y C385xD880. La primera cruza mostró una heterosis promedio y sobre el mejor progenitor de 4,9% y 4.1%, respectivamente; mientras que la segunda, tuvo similarmente una heterosis del 30% sobre un progenitor. A partir de 1999, los progenitores de la mejor cruza se mejorarán mediante un sistema de selección recurrente recíproca de medios hermanos, dos años por ciclo

Estudio de las principales plagas del nanche ["Byrsonima crassifolia" (L.) HBK] en Nayarit, México

The nance (Byrsonima crassifolia) is consistently attacked by insects that can be considered its main pests.The nance pests that have been found are: fruitworm (Cryptophebia spp.; Lepidoptera: Tortricidae), dried fruit weevil (Carpophilus spp.; Coleoptera: Nitidulidae), the nance spittlebug (Clastoptera spp.; Hemiptera: Clastopteridae), tree parakeet (Membracis Mexicana; Homoptera: Membracidae), green scale (Coccus viridis; Hemiptera: Coccidae) and the mealybug (Planoccus citri; Hemiptera: Pseudococcidae).El nanche (Byrsonima crassifolia) es atacado en forma consistente por insectos que pueden considerarse sus principales plagas. Las plagas del nanche que se encontraron son: gusano del fruto (Cryptophebia spp.; Lepidoptera: Tortricidae), gorgojo de las frutas secas (Carpophilus spp.; Coleoptera: Nitidulidae), salivazo del nanche (Clastoptera spp.; Hemiptera: Clastopteridae), periquito de los árboles (Membracis mexicana; Homoptera: Membracidae), escama verde (Coccus viridis; Hemiptera: Coccidae) y el piojo harinoso (Planoccus citri; Hemiptera: Pseudococcidae)

Aptitud combinatoria general y específica de líneas tropicales de maíz usando probadores

Thus, during autumn - winter season in 1996/97, there were evaluated in Cotaxtla, Ver. top crosses of tropical maize lines derived of several sources of germplasm such as: a) Recycled lines from H-513XVS-536, b) lines derived from a compound of wide genetic base (CABG3), c) Elite lines from Cotaxtla maize program and d) CIMMYT lines . There were used as testers, the lines LT154, and LT155 which are parents of H-513 and CML247 and CML254 which cross is an heterotic pattern defined by CIMMYT for the tropic . There were found lines like F31 x F30-4-3, F41 x F40-1-2, CABG3’-12-2-1-2-1, LT-174 y CML55 that registered good specific combining ability with tester 2 (LT-155) ;and F4 x F3-5-2 and CML15,with tester 4 (CML 254). On the other hand F4 x F5-5-1, CABG3’-12-2-1- 2-1, LT-174, CML13 and CML 15 had the best general combining ability. In relation with testers, it was found for recycled lines, that testers LT154 and CML254 registered the highest values for regression coefficients; It indicates that these testers identify the best lines; In lines derived from CABG3, tester LT155 registered the best value; In Elite lines, testers 2(LT155) and 3(CML247) identified better lines and from CIMMYT lines the best tester was CML254.Durante el ciclo O - I 1996/97 fueron evaluados en el Campo Experimental Cotaxtla mestizos de líneas sobresalientes y provenientes de varias fuentes de germoplasma como son : a) Líneas recicladas de H-513 X VS-536, b) Líneas derivadas de un compuesto de amplia base genética, c) Líneas élite de programa de maíz de Cotaxtla (LTs) y d ) Líneas de CIMMYT (CMLs). Como probadores se usaron las líneas LT-154 y LT-155 progenitores del híbrido H-513 y las líneas CML247 y CML254 cuya cruza es un patrón heterótico definido por CIMMYT para el trópico. Hubo líneas con buen comportamiento per-se tanto en rendimiento como en características agronómicas y que se encuentran formando mestizos sobresalientes con uno o varios probadores. Con relación a la Aptitud combinatoria, se encontró que las líneas F31XF30-4-3-1, F41XF40-1-2-1, CABG3’-12-2-1-2-1-1, LT174 y CML15 registraron los máximos valores con el probador 2 (LT155); F4XF3-5-2-1 y CML15 con el probador 4 (CMl254). Así también, las líneas F4XF5-5-1-1, y CABG3’-12-2-1-2-1-1, LT174, CML13 y CML15 con buena ACG. Con relación a los probadores, se encontró que para el grupo de líneas Recicladas , los probadores 1(LT154) y 4 (CML254) registraron los coeficientes de regresión más altos, lo que indica que permiten identificar líneas sobresalientes. Para líneas CABG fué el probador 2 (LT155) el que registró el mejor valor y en líneas Élite , los probadores 2(LT155), y 3(CML247) identificaron mejor a las líneas sobresalientes. Para las líneas del CIMMYT el mejor valor fué para el probador 4(CML254)

Efecto de suplementación con harina de aguacate en dietas de corderos sobre crecimiento y el rendimiento de la canal

To evaluate the inclusion of avocado meal (AM) in diets for sheep (0, 2.5, 5 and 10%) with a forage:concentrate ratio 40:60, on productive behavior and carcass characteristics. Ninety-six Pelibuey- Dorper male lambs with an average initial weight of 32.83 ±0.707 kg, eight animals per treatment, in a 4x3 four diets and factorial arrangement with feeding periods of 28, 56 and 84 days were used. Final weight and slaughter weight increased (p <0.05) with 10% inclusion compared to the control. In daily weight gain, feed intake, carcass weight and intramuscular fat, values were equal (p >0.05) with the inclusion of 10% AM and 0% AM. Feed conversion, DM, CP, energy and carcass yield efficiencies did not improved with AM. The longer the intake time (56 and 84 days), the higher the daily weight gain, feed intake, feed efficiency of DM, CP and energy (p < 0.05), and the lower the feed conversion rate, with no differences for final weight and carcass yield (p < 0.05). Daily gain and carcass weight indicate a slight positive trend due to the inclusion of 10% AM at 84 days. Inclusion does not affect the productive behavior of growth in sheepPara evaluar la inclusión de harina de aguacate (AM) en dietas para ovinos (0, 2.5, 5 y 10%) con una relación forraje:concentrado 40:60, sobre el comportamiento productivo y características de la canal. Se emplearon 96 corderos machos Pelibuey-Dorper con peso inicial promedio de 32.83 ±0.707 kg, ocho animales por tratamiento, en arreglo factorial 4x3 con cuatro dietas y periodos de alimentación de 28, 56 y 84 días antes del sacrificio. Peso final y peso al sacrificio incrementaron (p <0.05) con inclusión del 10% en comparación al control. En ganancia de peso diaria, consumo alimento, peso de la canal y grasa intramuscular, los valores fueron iguales (p >0.05) con inclusión de 10% AM y la del 0%. La conversión alimenticia, eficiencias de DM, CP y de energía, y el rendimiento de la canal no se mejoran con AM. A mayor tiempo de consumo 56 y 84 días aumentan (p <0.05) ganancia de peso por día, consumo alimento, eficiencias alimenticias de DM, CP y energía, y disminuye conversión alimenticia, sin diferencias para peso final y canal. Ganancia diaria y peso de la canal indican una ligera tendencia positiva por la inclusión de AM al 10 % por 84 días. La inclusión no afecta el comportamiento productivo del crecimiento en ovino