Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias
Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias
Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias
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16 t h International Congress on Animal <strong>Reproduction</strong><br />
Poster Abstracts 83<br />
P166<br />
Short term nutritional supplementation improves<br />
reproductive performance <strong>in</strong> ewes ma<strong>in</strong>ta<strong>in</strong>ed un<strong>de</strong>r<br />
extensive conditions <strong>in</strong> arid central Mexico<br />
Muñoz-Gutiérrez, M 1 *; Scaramuzzi, RJ 2 ; Escobedo Alcántara, JC 3 ; Trejo-<br />
González, A 4 ; Retana-Márquez, MS 1 ; Damian-Matzumura, P 1 and Borregos<br />
<strong>de</strong> Patria Nueva, AC 5<br />
1Reproductive Biology Departament, Universidad Autónoma Metropolitana<br />
Iztapalapa 09340 Mexico City, Mexico; 2 Department of Veter<strong>in</strong>ary Basic<br />
Sciences, Royal Veter<strong>in</strong>ary College, Hawkshead Lane, North Mimms Herts<br />
AL9 7TA, United K<strong>in</strong>gdom; 3 Fundación Mexicana para el Desarrollo Rural<br />
Tepeji <strong>de</strong>l Río A.C. 42850 Hidalgo, México; 4 Medic<strong>in</strong>a Veter<strong>in</strong>aria y<br />
Zootecnia. <strong>Facultad</strong> <strong>de</strong> Estudios Superiores Cuautitlán, Universidad Nacional<br />
Autónoma <strong>de</strong> México, 54700 Cuautitlán Estado <strong>de</strong> México, Mexico;<br />
5Comunidad <strong>de</strong> Patria Nueva Hidalgo, Mexico<br />
In the arid regions of Mexico (Hidalgo, Central Mexico) sheep are<br />
managed un<strong>de</strong>r extensive conditions on pastures that are of poor<br />
nutritive value. The <strong>de</strong>velopment and transfer of a simple and<br />
<strong>in</strong>expensive technology to improve the reproductive performance of<br />
these flocks would be a significant economic benefit to these<br />
subsistence farmers. Short-term nutritional supplementation of ewes<br />
with a high energy and high prote<strong>in</strong> diet for the last three days of the<br />
oestrous cycle <strong>in</strong>creases litter size of sheep managed un<strong>de</strong>r more<br />
favourable graz<strong>in</strong>g conditions <strong>in</strong> Australia, Uruguay and Europe. The<br />
present trial was carried out to <strong>de</strong>term<strong>in</strong>e if short-term nutritional<br />
supplementation of ewes graz<strong>in</strong>g poor quality pasture <strong>in</strong> the arid zone<br />
on central Mexico could improve their fertility. Seventy five mixed<br />
breed (Corriedale X Rambouillet X Suffolk) adult cycl<strong>in</strong>g ewes<br />
(median BCS = 2) were treated <strong>in</strong> the breed<strong>in</strong>g season for 11 days<br />
with progestagen sponges and 500 IU of eCG <strong>in</strong>jected on the day of<br />
sponge removal. The animals were supplemented for seven days with<br />
a diet consist<strong>in</strong>g of 250 g of rolled corn, 140 g of soya bean and 950 g<br />
of alfalfa hay per animal per day. The diet was offered to the animals<br />
start<strong>in</strong>g three days before sponge removal and cont<strong>in</strong>u<strong>in</strong>g until four<br />
days after sponge removal. Twenty seven control ewes were allowed<br />
to graze the available native pasture and their oestrous cycles were not<br />
synchronized. The proportions were analyzed us<strong>in</strong>g the Chi squared<br />
test. Follow<strong>in</strong>g the <strong>in</strong>troduction of fertile males, 81% (61/75 females)<br />
of the ewes fed the supplement displayed oestrous behaviour 1.54 ±<br />
0.05 days (mean ± SEM) after sponge removal and all 61 animals<br />
became pregnant at the <strong>in</strong>duced cycle. Of the 27 control ewes only 8<br />
(30%) mated and only 5 (18.5%) became pregnant (P 70 days after lamb<strong>in</strong>g. Ovarian activity was<br />
consi<strong>de</strong>red as cyclic if the P4 level was more than 3.2 nmol/l at least<br />
<strong>in</strong> one sample, e.g. <strong>in</strong> 20 (37%) and 13 (43%) of the HPM and TS<br />
ewes, respectively. The distribution of various MnII and RsaI<br />
genotypes was quite similar <strong>in</strong> the two breeds (<strong>in</strong> HPM: MnII<br />
AA=19%, AB=51%, BB=31%; RsaI AA=23%, AB=56% BB=21%;<br />
<strong>in</strong> the TS: MnII AA=14%, AB=54%, BB=32%; RsaI AA=11%,<br />
AB=61%, BB=28%; <strong>in</strong> case of both RFLP sites allele “A” means the<br />
absence of the cleavage site). Association between genotypes and<br />
seasonality was significant (P