Influence Of Rams Research Articles

Влияние баранов-производителей на молочность маток-дочерей карачаевской породы и динамику живой массы их потомства

Влияние баранов-производителей на молочность маток-дочерей карачаевской породы и динамику живой массы их потомства

The effect of service ram on reproductive performances and birth weight of lambs

The investigation was conducted in population of Mis breed of sheep, divided into three groups. For reproduction had use rams of Ile de France breed. Induction and synchronization of oestrus was done off-season in October. The percentage of lambing sheep, sheep fertility, and number of lambs acquired per father, sex and birth type of lambs were observed. Ram 1 had a highest number of ewes lambed with an excellent percentage of mating success and highest fertility rate of ewes with differences on fertility rate of 17% (between group of ewes in ram 1 and ram 2), 36% (group of ewes in ram 1 and ram 3) and 19% (group of ewes in ram 2 and ram 3).The highest birth weight were on lambs born single from ram 3, born twins from ram1, triplets of ram 3. For the lambs born quadruplets (unfortunately only in rams 1 and 2 with one lamb of each was alive) the lamb of ram 2 was higher in birth weight. The male and female lambs of ram 3 got the highest birth weight while the female lambs of ram 1 acquired the lowest birth weight. The highest average birth weight of lambs was born single, male; born triplets? male from lambs of ram 3 having an average birth weight of 6.36kg and 4.0 kg but got the lowest for lambs born twins on female lambs 3.66 kg. The male lambs of ram 1 got the highest average birth weight on lambs born twins with an average birth weight of 4.38 kg but the lowest on triplets born 3.3kg. Unfortunately only one each of the two ram with lambs born quadruplets alive both male and the higher was that lamb of ram 2 with a birth weight of 3.3 kg. Result showed the influence of ram on number of lambs born and lambs? birth weight. Between subject effects Father* birth type showed a significant effect on birth weight of lambs.

The influence of ram on litter size in Suffolk sheep

The proportion of variance for service ram effects was estimated for number lambs born and weaned. The database with 11,311 lambings in purebred Suffolk was used. The basic model equation for the analysis of variance of litter size contained effects of ewe´s age at lambing, contemporary group of ewes at lambing, ewe´s permanent environmental effect and ewe´s direct additive genetic effect. The other models were extended by contemporary group of ewes during mating (harem), and additive genetic and permanent environmental effect of service ram. Variance components were estimated by the Gibbs sampling method. The proportions of variance for the service ram effect for number of lambs born and weaned were 4.1 % and 2.6 %. The annual genetic trends were 0.4 % of lambs born and 0.2 % of lambs weaned for female fertility. Male contribution on litter size was 0.2 % of lambs born and 0.1 % of lambs weaned. The results demonstrated that service rams in Suffolk sheep have low influence on litter size of their mates.

A note on ram preference by oestrous ewes: Influence of rams’ age and sexual performance

Ewes in oestrus, besides being receptive to rams, develop an active search for them. We performed two experiments to determine if oestrous ewes prefer: (1) high or low sexual-performance rams, and (2) 2-year-old or aged (>8-years-old) rams. In the first experiment, the preference of ewes for rams with high or low sexual performances was compared in 16 tests. In the second experiment, 17 tests were performed comparing ewes’ preference for aged rams (>8-years-old) or young rams (2-years-old). In each test, two rams were tied at equal distances from the point of entrance of the ewe, with a maximum mobility for each ram of 2 m. The first approach to a ram, the quantity of approaches toward each ram (less than one body length), and the total time that the ewe remained near each ram were registered during 5 min. Oestrous ewes did not display any preference according to sexual performance of rams, but spent significantly more time ( P = 0.02), and did it in more tests ( P = 0.025), with young than with aged rams. Ewes also tended to approach first ( P = 0.07), and more times in more tests ( P = 0.06), to young than to aged rams. We conclude that ram's sexual performance seems not to influence oestrous ewes preference, and that ewes’ prefer young (2-years-old) rather than aged rams (>8-years-old).

Closed die forging analysis of polycarbonate using an upper bound approach

A model for the closed die flashless forging of a work-hardening polymer material (polycarbonate) is developed using an upper bound approach. Deformed geometry, effective strains and stresses are computed at various stages in the upsetting process. The influence of ram and die wall friction is considered through the formation of dead zones within the workpiece after it makes contact with the die surface. Both axisymmetric and plane strain cases are investigated in the analysis, and results of plane strain compression experiments are compared with analytical predictions. Strain measurements show good agreement for initial billet dimensions of height to width ratios greater than one. The simplifying assumptions made in the model formulation and possible causes for discrepancies are discussed.

自然交配における雌羊の繁殖成績に及ぼす種雄羊の影響

[in Japanese]

Proceedings: the influence of rams on the fertility of the ewe.

Proceedings: the influence of rams on the fertility of the ewe.

The influence of rams on onset of oestrus in Merino ewes in the spring

Association with rams had a stimulating influence on the onset of oestrus after anoestrus in the spring. Smell and sound of the rams was sufficient to provide the stimulating influence. Direct contact with rams certainly was not necessary. Ewes which had been held well separated from rams from the beginning of July were permitted varying degrees of association with rams for 11–12 hr daily for 2 weeks in November. Some could smell, hear, see, and have actual contact with the rams; others could smell, hear, and see them only; others could smell and hear them only. These ewes, along with others which had remained well separated from rams during the same period, were then run together with raddled vasectomized rams continuously. Almost all ewes experienced oestrus during the following 26 days. However, most ewes which had previously had some association with rams experienced it first within 17 days whereas most of those which had been previously kept separate from rams did so between the 18th and the 26th day. The results in all groups which were associated with rams were closely similar irrespective of the nature of the association.

Influence of rams on ovarian activity and oestrus in Merino ewes in the spring and early summer

The occurrence of oestrus and ovulation and the changes in the vaglnal contents were studied in Merino ewes following the introduction of vasectomized rams at various times during the spring and early summer. The ewes were in an anoestrous state when the observations were commenced. Except in occasional ewes oestrus did not appear until early December. It had occurred in all except a few ewes by early January. In most ewes among which rams were introduced on October 26 or November 18, it occurred about a week earlier than in ewes among which rams mere not introduced until December 8, and ewes among which rams had been running continuously. In at least 80 per cent, of animals in which both were studied, oestrus was accompanied by massive desquamation of the vaginal epithelium and it was preceded by one or more periods of massive desquamation. Between December 8 and December 14, masses of desquamated epithelial cells were present in the vaginal contents in few only of the ewes which were held separate from rams, but in almost all ewes among which rams were introduced on December 8 (group 4), and in most of the em7es which were running continuously with rams (group 6). They first appeared in the ewes of group 4 between December 11 and December 14, 3-6 days after the introduction of the rams, whereas they were already present in almost all of the ewes of group 6 by December 11.Corpora lutea compatible with ovulation shortly after December 8 were present in most ewes among which rams were introduced on that day, and in few ewes which were held separate from rams. The significance of these results is discussed.