Estrus Grouping in Sheep Treated with Melengestrol Acetate （MGA）

In Mexico the predominant sheep production system is the semi-extensive with grazing during the day and stanchion afternoon and night. Sheep herd are usually small, approximately 10 to 75 heads. The objectives of these systems are savings and marketing of lambs. Meat is the main economic product of this kind, the breeding is long, which do not control the delivery dates and ages of the sheep are not uniform, affecting the demand for the local market （for the months of June and December）. Therefore the aim of this work was implement a technology that allows the grouping of the estrus and therefore group deliveries for batches of uniform lambs. This technology was designed to suppress the estrus and heifers growth promoter of feedlots, this technology is melengestrol acetate （MGA） which is a synthetic progesterone oral administration that it is easy to manage in the food or alone, economic that it does not represent any risk for sheep females of abortive type, evaluating the effect of the MGA on rate of estrus and gestation in sheep. Work developed in the municipality of Charo from Michoac^in State, M6xico, 20 hair sheep divided in two groups of 10 female, group one treated with MGA and group tow was the whitens. 100% of the sheep treated with a dose of 0.45 mg MGA/head/day for 17 days orally, presented estrus grouped in 5-10 days; however only 50% of the sheep of the witness group presented estrus. In the experimental group there was a rate of 70% with a gestation difference time of no more than ten days gestation and witness group 50%. The MGA is an efficient alternative for the producer of sheep when administered 0.45 mg MGA/head/day for 17 days because inhibits the estrus and once withdrawn treatment manifests estrus synch with which get a rate of gestation elevated by natural riding.

The Use of Melengestrol Acetate as a Strategy to Improve Production Efficiency of Sheep in Rural Areas in Mexico

The aim of this study was to evaluate the use of melengestrol acetate （MGA） as a strategy to improve the production efficiency in ewes of rural areas in Mexico. Twenty ewes of breeds （Dorper and Dorper with Pelibuey） non-pregnant and with ovarica activity were used. The treatment consisted of the administration of 0.22 mg MGA/ewe/d for 17 d. The MGA efficiency was measured once the treatment finalized, and the producer was responsible for the registration of the estrus presentation and prolificacy rate. 95% of the sheep presented estrus in a period of 14 d after stopping treatment. The prolificacy percentage was of 1.2 lambs born by ewe during a period of six months （including treatment and period of gestation）. In conclusion, the use of MGA represents an alternative to improve the efficiency of sheep production in rural areas in Mexico, since it can increase the number of lambs by 30% in a period of 12 months.

Abiotic transformation of synthetic progestins in representative soil mineral suspensions

Altrenogest(ALT),drospirenone(DRO),and melengestrol acetate(MLA)are three highly potent synthetic progestins that can be released into agricultural soils,while their fate in soil minerals remains unclear.This study explored the transformation of these progestins in MnO_(2),SiO_(2),and ferrihydrite suspensions and identified their transformation products(TPs)via high resolution mass spectrometry and density functional theory calculations.Transformations were only observed for DRO and MLA in SiO_(2) suspension and ALT in MnO_(2) suspension(half-lives=0.86 min–9.90 day).ALT transformation was facilitated at higher MnO_(2) loadings,while DRO and MLA transformations were inhibited at higher SiO_(2) loadings.These data indicated that hydrophobic partitioning interactionwas dominant at higher SiO_(2) loadings rather than specific interaction,which limited subsequent surface-catalyzed transformation.ALT transformation rate decreased with increasing pH because MnO_(2) reduction requires proton participation.In contrast,relatively high pH facilitated MLA and DRO transformation,indicating that base-catalyzed hydrolysis occurred in SiO_(2) suspension.The clustermap demonstrated the formation of abundant TPs.Lactone ring and acetoxy group hydrolysis was the major transformation pathway for DRO and MLA,with estimated yields of 57.7%and 173.2%at 6 day,respectively.ALT experienced C12 hydroxylation and formed the major TP 326g(yield of 15.4%at 8 hr).ALT also experienced allyl group oxidation and subsequent C5 hydroxylation,forming the major TP 344a(yield of 14.1%at 8 hr).This study demonstrates that TPs ofmetastable progestins are likely the main species in soils and that TP identification is a particular priority for risk assessment.