Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 3 de 3
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Transl Anim Sci ; 6(1): txac019, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35237747

RESUMO

Ruminants serve a valuable role in sustainable agricultural systems, specifically in the conversion of renewable resources from grasslands, pasture, and other by-products into high-quality human food. Recognizing forage and grasses are grown on 25% of arable land, suitable agronomic practices for management of grazing livestock are necessary for the economic sustainability of the livestock enterprise, whereas at the same time, minimizing water and soil erosion. Demographics of undergraduate animal science students have changed over the last several years with more students from urban backgrounds and with interests other than traditional animal agriculture. Thus, continued emphasis on education programs supporting grazing livestock industries becomes that much more important. In addition, newer technologies to measure production on range and pastureland have emerged, thereby increasing opportunities for further training and education. Based on an email assessment of 10 land grant institutions, typically one MS student/yr and one PhD student/3 to 4 yr graduates with an advanced degree in forage agronomy. Overall budget reductions which impact operational costs, internal funding for research projects and graduate student stipends, force universities to focus in areas with the best chance of monetary return. Challenges with funding faculty positions outside of a department's emphasis area typically result in the question "Should forage agronomy students be trained in Departments of Animal Science or Agronomy/Plant/Soils Sciences?" It could be argued that either department is the best fit. Forage agronomy requires training in the basics of plant and soil science, but the application of those sciences within a Department of Animal Science relates more to animal science/production than to traditional crop production such as cereal grains. Animal science departments must communicate the meaningful context of forage agronomy in an active learning environment developing students' ability to critically think and solve problems. Those providing technical expertise to livestock producers can no longer make recommendations based solely on production efficiency and profitability. Instead, best management practices must include the impact of grazing livestock on the environment and environmental sustainability. Cooperative agreements between departments should be discussed to adequately support student development in this critical subject matter.

2.
J Anim Sci Biotechnol ; 4(1): 20, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23710543

RESUMO

BACKGROUND: Integration of behavioral observations with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems. Brahman-influenced (BR; n = 64) and Gelbvieh × Angus (GA; n = 64) heifers consumed either toxic endophyte-infected tall fescue (E+) or one of two nontoxic endophyte-infected tall fescue (NT) cultivars during two yr. Heifers were weighed at midpoint and termination of grazing. Grazing behavior (grazing, resting in the shade, lying, or standing without grazing) was recorded (n = 13 visual observations per yr in June and July) for each pasture. During yr 2, exit velocity (EV) and serum prolactin (PRL) were determined. RESULTS: Grazing behavior was influenced (P < 0.05) by an interaction between fescue cultivar and breed type. Gelbvieh × Angus heifers assigned to E+ pastures had the lowest percentage of animals grazing and the largest percentage of animals resting in the shade. Brahman-influenced heifers had faster EV (P < 0.001) than GA heifers (0.52 vs. 0.74 ± 0.04 s/m, respectively). Body weight (BW) was affected (P < 0.01) by an interaction of tall fescue cultivar and d, and an interaction of tall fescue cultivar and breed type. Heifers grazing NT pastures were heavier (P < 0.01) than heifers grazing E+ pastures at midpoint and termination. Gelbvieh × Angus heifers grazing NT pastures were heavier (P < 0.01) than GA and BR heifers grazing E+ and BR heifers grazing NT pastures. An interaction of forage cultivar and breed type occurred on serum PRL (P < 0.01). CONCLUSION: Collectively fescue cultivar, EV, and concentrations of serum PRL were associated with grazing behavior. Heifers grazing NT pastures were observed to be grazing more than heifers assigned to E+ pastures, regardless of breed type, which may have contributed to changes in BW and average daily gain (ADG) in heifers. Integration of behavioral observations along with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems.

3.
In Vitro Cell Dev Biol Anim ; 45(8): 483-9, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19452232

RESUMO

There is evidence that ergot alkaloids can directly interact with mammalian spermatozoa affecting sperm functions. Ergot alkaloids exert their toxic or pharmaceutical effects through membrane receptor-mediated activities. This study investigated the signaling pathways involved in the in vitro inhibitory effects of both ergotamine (ET) and dihydroergotamine (DEHT) on the relative motility of bovine spermatozoa using specific inhibitors. Motile bovine spermatozoa were prepared using a Percoll gradient and incubated with ergot alkaloids with and without signaling pathway inhibitors. Co-incubation of ET or DHET with 100 microM prazosin (alpha 1-adrenergic receptor inhibitor) decreased (p < 0.05) relative motility of spermatozoa when compared with controls. In addition, preincubation of spermatozoa with 10 or 20 microM prazosin and DHET also reduced (p < 0.05) the number of motile spermatozoa. Relative sperm motility (motility of treated spermatozoa normalized to control sperm motility) was increased (p < 0.05) when co-incubations included ET and yohimbine (alpha 2-adrenergic receptor inhibitor); conversely, co-incubation of yohimbine (100 microM) and DHET decreased (p < 0.05) the percentage of motile spermatozoa when compared with controls. Pertussis toxin and cholera toxin (effectors of inhibitory and stimulatory G-proteins, respectively) altered (p < 0.05) relative sperm motility in a concentration dependent manner; however, co-incubation of pertussis or cholera toxin with ergot alkaloids had no interactive (p = 0.83) effects on the relative motility of spermatozoa. Co-incubation of Rp-cAMP (a membrane-permeable cAMP inhibitor) with 50 microM DHET had no effect (p > 0.05) on relative sperm motility; whereas, the co-incubation of 22.4 or 44.8 microM Rp-cAMP with 50 microM ET increased (p < 0.05) the percentage of motile spermatozoa when compared with 0 or 224 microM Rp-cAMP (49%, 65%, 59%, and 54%, respectively, for 0, 22.4, 44.8, and 224 microM of Rp-cAMP. An interaction between BAPTA-AM (a chelator of intracellular calcium) and alkaloids also impacted (p < 0.05) relative sperm motility. Generally, co-incubating spermatozoa with BAPTA-AM and ET increased the percentage of motile spermatozoa; however, co-incubation with DHET decreased relative sperm motility except with 41 microM BAPTA-AM. Collectively, these observations suggest that ET and DHET decreased the percentage of motile bovine spermatozoa via alpha adrenergic receptors. However, the second messenger systems involved with ergot alkaloid inhibition of relative motility of bovine spermatozoa remain to be elucidated.


Assuntos
Alcaloides de Claviceps/farmacologia , Transdução de Sinais , Motilidade dos Espermatozoides/efeitos dos fármacos , Espermatozoides/efeitos dos fármacos , Animais , Bovinos , Quelantes/farmacologia , Toxina da Cólera/farmacologia , AMP Cíclico/análogos & derivados , AMP Cíclico/farmacologia , Di-Hidroergotamina/farmacologia , Ácido Egtázico/análogos & derivados , Ácido Egtázico/farmacologia , Ergotamina/farmacologia , Masculino , Toxina Pertussis/farmacologia , Prazosina/farmacologia , Receptores Adrenérgicos alfa/efeitos dos fármacos , Receptores Adrenérgicos alfa/metabolismo , Transdução de Sinais/efeitos dos fármacos , Motilidade dos Espermatozoides/fisiologia , Ioimbina/farmacologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...