Sequence variation of the alpha-lactalbumin gene in Holstein and Nellore cows

The alpha-lactalbumin is a subunit of lactose-synthase, an enzyme responsible for lactose production, a disaccharide that influences milk production. Sequence variations of bovine alpha-lactalbumin have been associated with differences in milk yield. This study aimed to analyze allelic frequency differences at position-1689 (g. AG) and+15 (g. AG) of the alpha-lactalbumin gene in Holstein (Bos taurus) and Nellore (Bos indicus) cows. Blood samples were analyzed from 34 Holstein, 104 Nellore, and 99 Dairy Nellore cows using PCR-RFLP. The different RFLP patterns were sequenced and a novel sequence variation on nucleotide-46 was identified. An adenine at this position was designated as the A allele and a guanine was designated B allele. The frequencies of alleles A-1689, A-46, and A+15 differed between Holstein and both Nellore breeds. The results show that differences in alpha-lactalbumin allelic variants in the 5`-flanking and the 5`-UTR region might be associated with differences in milk production between Holstein cows and cows from Nellore breeds. However, the lack of difference between Nellore and Dairy Nellore suggests that other sequence variantions that regulate milk production might be responsible for the selection of Dairy Nellore cows with superior milk production.

Differences in thermoregulatory ability between slick-haired and wild-type lactating Holstein cows in response to acute heat stress

Animals inheriting the slick hair gene have a short, sleek, and sometimes glossy coat. The objective of the present study was to determine whether slick-haired Holstein cows regulate body temperature more effectively than wild-type Holstein cows when exposed to an acute increase in heat stress. Lactating slick cows (n = 10) and wild-type cows (n = 10) were placed for 10 h in an indoor environment with a solid roof, fans, and evaporative cooling or in an outdoor environment with shade cloth and no fans or evaporative cooling. Cows were exposed to both environments in a single reversal design. Vaginal temperature, respiration rate, surface temperature, and sweating rate were measured at 1200, 1500, 1800, and 2100 h (replicate 1) or 1200 and 1500 h (replicate 2), and blood samples were collected for plasma cortisol concentration. Cows in the outdoor environment had higher vaginal and surface temperatures, respiration rates, and sweating rates than cows in the indoor environment. In both environments, slick-haired cows had lower vaginal temperatures (indoor: 39.0 vs. 39.4 degrees C; outdoor 39.6 vs. 40.2 degrees C; SEM = 0.07) and respiration rate (indoor: 67 vs. 79 breaths/min; outdoor 97 vs. 107 breaths/min; SEM = 5.5) than wild-type cows and greater sweating rates in unclipped areas of skin (indoor: 57 vs. 43 g.h(-1)/m(2); outdoor 82 vs. 61 g.h(-1)/m(2); SEM = 8). Clipping the hair at the site of sweating measurement eliminated the difference between slick-haired and wild-type cows. Results indicate that slick-haired Holstein cows can regulate body temperature more effectively than wild-type cows during heat stress. One reason slick-haired animals are better able to regulate body temperature is increased sweating rate.

The effect of sodium chloride supplementation on the milk production of grazing Holstein Friesian cows during summer and autumn in a humid sub-tropical environment

Two studies were conducted to examine the effects of including NaCl at various rates in grain-based supplements for Friesian cows grazing established, dominant (>90%), rainfed kikuyu (Pennisetum clandestinum cv. Common) pastures during summer and autumn in a humid sub-tropical environment. In study 1 (19 January-27 March 1998), 48 cows (36 multiparous, 12 primiparous; 27-96 days postpartum) were allocated to one of four groups based on genetic merit, milk production, liveweight (LW) and days postpartum. They were fed (2.7 kg dry matter (DM) per cow, twice-a-day) one of four isoenergetic and isonitrogenous barley grain-based concentrates containing NaCl at concentrations (% as-fed) of either 0 (SC1), 1.1 (SC2), 2.2 (SC3) or 3.3 (SC4). Maximum temperature humidity index (THImax) was greater than or equal to78 during 50% of the experimental period. Concentrate NaCl content had no effect (P>0.05) on daily milk yield or LW change but daily yields of 4% fat corrected milk (FCM), fat and protein were higher (P0.05) among treatments at 7.6+/-1.24 kg DM per cow. In study 2 (18 January 1999-1 March 1999), 48 cows (32 pluriparous, 16 primiparous: 32-160 days postpartum) were fed (2.7 kg DM per cow twice-a-day) one of two isoenergetic and isonitrogenous barley grain-based concentrates containing NaCl at concentrations (% as-fed) of 0 (control) or 2.2 (HSC). THImax was greater than or equal to78 during 34% of days in the experimental period. Yields of milk, FCM, fat and protein were lower (P0.05) by concentrate NaCl content. These studies indicate that NaCl supplementation can be beneficial in terms of milk production during warm, humid conditions as opposed to milder conditions. (C) 2002 Elsevier Science B.V. All rights reserved.

Morphometry of testis and seminiferous tubules of the adult crab-eating fox (Cerdocyon thous, Linnaeus, 1766)

Body and testicular biometric parameters are very important for establishing reproductive patterns and, consequently, the development of protocols for assisted reproduction in different species. A direct correlation between the testis weight and the sperm population was observed in other studied species, because the testis size primarily reflects the total volume of the seminiferous tubule, its main component. The objective of this study was to determine the testicular volume parameters and correlate data from morphometry of testis and seminiferous tubules with body mass in six adult crab-eating foxes. The mean body weight of the crab-eating foxes in this study was 6.53 kg, with approximately 0.068% allocated to the testicular mass and 0.042% specifically to seminiferous tubules, which represented 87.5% of the testicular parenchyma. The albuginea comprised 12.5% of the testicular mass. The mean diameter of seminiferous tubules was 236 µm, and the mean thickness of the seminiferous epithelium was 62.9 µm. Values of tubular parameters indicate a sperm productivity close to those observed in previously studied carnivores.

Effect of hay on performance of Holstein calves at suckling and post-weaning

The objective of this work was to evaluate the performance of Holstein calves in suckling and post-weaning phases, intensively managed during suckling in the absence or presence of hay. Twenty-four male Holstein calves, at an average age of 15 days and initial weight of 43 kg were used in the experiment. The experimental design was completely randomized, consisting of two treatments and six replications. The treatments were as follows: 1) suckling with milk substitute + initial concentrate for calves, ad libitum + temperate grass hay (oat/ryegrass), ad libitum; 2) suckling with milk substitute + initial concentrate for calves, ad libitum. No significant difference was found between treatments for weight gain and feed conversion. However, the supply of hay caused an increase in daily dry matter intake (2.127 vs 1.894 kg). The intake of hay promoted greater stimulus to consumption of concentrate and greater weight at weaning.

Esterilidad individual en Rhodnius prolixus Stal. tratados con metepa (oxido de tris (1-(2 metil) aziridinil) fosfuro), y accion del mismo sobre Trypanosoma cruzi

Se analizan los factores que interfieren en la esterilidad inducida químicamente en R. Prolixus mediante aplicaciones tópicas en distintas dosis de metepa. Se sugiere profundizar el estudio de la susceptibilidad individual para conocer la composición de la población frente al quimioesterilizante y la probable aparición de resistencia. Se investiga además la acción del metepa sobre T. cruzi en triatominos infectados experimentalmente, obteniéndose resultados negativos.

Alguns aspectos da biologia de Lymnaea columella Say, 1817 (Gastropoda, Pulmonata)

Foram estudados aspectos da biologia da Lymnaea columella Say, 1817, em condições de laboratório e determinadas as variações da duração do período embrionário em relação à temperatura da água.

Ocorrência de infecção natural de Fasciola hepatica Linnaeus, 1758 em Lymnaea columella Say, 1817 no Vale do Paraíba, SP, Brasil

Foram registradas em Piquete, no vale do rio Paraíba do Sul (SP), Brasil, taxas de 1,22% e 0,14% de infecção natural em Lymnaea columella, por Fasciola hepatica. Em um único exemplar de Lymnaea columella dentre os 1.052 examinados, foram observadas rédias com xifidiocercárias, rédias com cercárias de Fasciola hepatica e metacercárias de Echinostomatidae.

Aspectos morfológicos de ovos de triatominae: II - Características macroscópicas e exocoriais de dez espécies do gênero Rhodnius Stal, 1859 (Hemiptera - Reduviidae)

Foi realizado estudo morfológico do exocório de ovos de dez espécies de Rhodnius (Hemiptera-Reduviidae) através de microscopia eletrônica de varredura e microscopia óptica, com vistas à classificação taxionômica: Rhodnius domesticus Neiva & Pinto, 1923; R. ecuadoriensis Lent & León, 1958; R. nasutus Stal, 1859; R. neglectus Lent, 1954; R. neivai Lent, 1953; R. pallescens Barber, 1932; R. paraensis Sherlock, Guitton & Miles, 1977; R. pictipes Stal, 1972; R. prolixus Stal, 1859; e R. robustus, 1927. São apresentados dados sobre aspectos gerais das cascas e dos ovos quanto à forma, coloração e tamanho, bem como as modificações que poderão ocorrer quanto à coloração durante o desenvolvimento embrionário pós-oviposição. São elaboradas chaves dicotômicas para a classificação destas espécies, baseadas na utilização de caracteres visíveis pela microscopia óptica e microscopia eletrônica de varredura.

Estudo de rendimentos queijeiros em leites das raças Holstein e Jersey numa exploração da ilha Terceira

Dissertação de Mestrado em Engenharia Zootécnica

Susceptibilidade de Lymnaea (pseudosuccinea) columella (Say, 1817) exposta à infecção por miracídios de Fasciola hepatica (Linnaeus, 1758)

Com o objetivo de estudar a susceptibilidade de Lymnaea (pseudosuccinea) columella de Minas Gerais, Estado onde ainda não se registraram casos autóctones de fasciolose hepática, foram utilizadas as amostras MG 1, MG 2, MG 3 e MG 4, provenientes de diferentes regiões deste Estado, para estudo comparativo com as amostras RJ e RGS procedentes dos Estados do Rio de Janeiro e Rio Grande do Sul, áreas de focos de fasciolose. A amostra de Fasciola hepatica utilizada era procedente de ovinos abatidos no município de Camapuã, no Rio Grande do Sul, e foi mantida em coelhos. Os moluscos foram infectados com 6, 8 e 10 miracídos por molusco, sendo estudadas as incidências de infecção e de mortalidade. Nas condições que se realizou o trabalho diante dos resultados obtidos, foram tiradas as seguintes conclusões: 1. A mortalidade dos caramujos parece não estar diretamente relacionada com a percentagem de infecção; 2. As amostras de Lymnaea (pseudosuccinea) columella de Minas Gerais, do Rio de Janeiro e do Rio Grande do Sul mostraram-se identicamente susceptíveis à infecção por Fasciola hepatica; 3. A população humana e os rebanhos bovino, ovino e suíno de Minas Gerais, particularmente aqueles do Vale do Rio Paraíba, podem ser considerados sujeitos à infecção por Fasciola hepatica.

Nota sôbre a presença do Rhodnius prolixus Stal, 1859, no Estado de São Paulo, Brasil (Hemiptera, Reduviidae, Triatominae)

Através de um lote de ninfas e adultos de Rhodnius, proveniente de Mira Estrela, Estado de São Paulo, assinalamos pela p rim e ira vez, a presença de Rhodnius prolixus nesse Estado.

Biology of Triatominae (Reduviidae Hemiptera) from North of Formosa County (Goiás-Brazil) I. Length of life cycle of Triatoma sordida (Stal. 1859)

In the present paper the life cycle of Triatoma sordida was studied. The mean length from egg to adult was 213 days. The mean length in days from each stage was: 24.3 (± 1.30) for the first. 32.8 (± 1.45) (2nd), 36.1 (± 1.50) (3rd), 44.6 (± 1.85) (4th) and 52.0 (± 1.92) (5th). The mean egg incubation períod was 23.2 (± 1.40). Overall mortality was 18.8% and egg viability was 82.5%.