Carlos Palacios

Effects of exogenous melatonin treatment on out-of-season ram fertility

Abstract Three field experiments were performed to determine the effects of melatonin implants on the fertility of rams. The experiments were performed on three breeds (Rasa Aragonesa, Assaf and Manchega) in three commercial farms in Spain. Melatonin-treated rams (M) and non-implanted control rams (C) mated either ewes oestrous-induced with FGA intravaginal sponges (Rasa Aragonesa and Assaf farms) or melatonin-treated ewes during the anoestrous period (Manchega farm). Scrotal circumference (SC) was measured at melatonin implantation and at ram introduction (nearly 45 d later). Lambing rate, litter size, and fecundity were recorded at parturition. Melatonin implants in rams increased the number of lambs born per ewe in Rasa Aragonesa (19%), Assaf (9%), and Manchega (7%) because of the higher lambing rates exhibited by ewes mated with melatonin-treated rams (Rasa Aragonesa: 80.2% vs 70.5%, P<0.05; Assaf: 74.2% vs 68.0%, NS; Manchega: 90.0% vs 81.5%, P<0.05; for M and C groups, respectively). As a result, the number of extra lambs born per treated ewe was 0.17, 0.10, and 0.10 in the Rasa Aragonesa, Assaf, and Manchega ewes, respectively. In the M and C groups of Rasa Aragonesa rams, mean scrotal circumference increased significantly between the start of the experiments and the onset of mating, but the two groups did not differ significantly at the implantation or at the onset of mating. In the melatonin-treated and control Assaf rams, scrotal circumference increased over the course of the experiments but, at the onset of mating, the melatonin-treated rams had higher SC than did the control rams. Melatonin-treated Manchega rams had scrotal circumferences that were significantly greater than those of the control rams. In the Rasa Aragonesa and Manchega breeds, treating rams using melatonin implants significantly increased the net lamb production of ewes in field conditions. In the Assaf breed, the number of extra lambs born per ewe mated with melatonin treated rams was lower than in the other breeds, even though rams exhibited a significant increase in scrotal circumference. Further research involving the study of semen quality has been planned.

Offspring sex ratio in sheep, cattle, goats and pigs: influence of season and lunar phase at conception

Abstract This study assessed the relationship between season and lunar phase at conception on offspring sex ratio of four livestock species (sheep, cattle, goats and pigs). The sex of 66,830 lambs (1995–2015); 25,546 calves (2011–2015); 5671 kids (2002–2007) and 1916 piglets was recorded. Moon phases were categorized as either new moon, crescent moon, full moon or decrescent moon. Sex ratio, expressed as proportion of males (males/males + females), was tested against the expected value of 1:1. In sheep, offspring sex ratio and lunar phase were not correlated; season had a significant (p = 0.002) effect on offspring sex ratio. The proportion of males born of spring and winter matings was significantly higher than it was among offspring born of summer (p < 0.05) or autumn (p < 0.01) conceptions. Offspring sex ratios in spring (p < 0.05), autumn (p < 0.01) and winter (p < 0.05) differed significantly from the expected. In cattle, moon phase and season did not affect the offspring sex ratio; however, the interaction effect was highly significant (p = 0.001). The overall piglet sex ratio (0.522), and the sex ratios among piglets conceived during a crescent moon and those conceived in summer differed significantly (p < 0.05) from 1:1. Research including additional factors such as hormonal treatments prior to insemination, food availability, weather and maternal and paternal factors might provide the underlying reasons for the effects of season and moon phase on offspring sex ratio in some livestock species.

Management and meteorological factors affect fertility after artificial insemination in Murciano-Granadina goats

Over 6 years, 2004 artificial inseminations (AI) were documented from 13 goat farms. We quantified the effect on fertility rate of management factors (farm, year, month, timing and order of insemination, dose of progestagen, prostaglandin, equine chorionic gonadotrophin and prostaglandin doses, age, technician, problems at AI, body condition and buck) and meteorological conditions at AI (mean, maximum and minimum temperatures, mean relative humidity, mean solar radiation, and total rainfall). Meteorological variables were converted to categorical variables to quartiles and deciles. Overall fertility was 56%. Each of the management factors had a significant (P < 0.05) effect on fertility. Non-pregnant goats differed significantly in most of the meteorological variables. Successful inseminations were associated with significantly (P < 0.001) higher mean, maximum and minimum temperatures, and solar radiation, and lower relative humidity, and rainfall, than were failed inseminations. Fertility rates of the highest and lowest deciles were significantly different for each of the meteorological variables. Inseminations performed when meteorological values were in the highest decile of mean (62%), maximum (61%) and minimum temperature (60%), and solar radiation (59%), and the lowest of relative humidity (61%) and rainfall (57%) had a significantly (P < 0.0001) higher proportion of does that became pregnant than when meteorological values were within the opposite decile (47%; 34%; 55%; 46%; 45%, and 43%, respectively). In conclusion, management and meteorological factors affected the success of AI in goats. Although technical factors can be controlled, it remains to be determined whether scheduling the dates of insemination based on forecasted temperatures can improve the success of AI.

Supernumerary Teat Removal Can Be Avoided in Dairy Sheep

The aim of this work was to determine whether the removal of supernumerary teats from dairy sheep when they are born is a useful procedure in the farming routine. Ewes were divided into 3 groups according to the number of teats at milking: ewes who were born with 2 teats; ewes who were born with 4 teats and had the 2 supernumerary nipples cut just after birth; and ewes who were born with 4 teats and did not have nipple amputation performed. Removal of supernumerary teats at lambing produced a significant reduction in milk production during the 2 first milking periods (p < .01). There were no differences between ewes with 2 or 4 teats, which suggests that this procedure is not necessary on dairy sheep farms. Because the presence of supernumerary teats is highly heritable, the elimination of this trait could be accomplished through selection methods.

Nutritive value for ruminants of winter oats–legume intercrops in organic cultivation

Winter oats were grown according to European organic farming regulations in monoculture (oats) and in intercropping with bard vetch (BAV), bitter vetch (BIV) or both legumes (MIX) to evaluate the effects of intercropping on forage yield and nutritive value for ruminants. The experiment was carried out as a randomised complete block design with four replications, and whole forage samples were obtained at two harvest dates (June and July). For both harvest times, all intercrops increased (P < 0.05) forage yield compared with oats, but forage crude protein content was only increased (P < 0.05) for BAV and MIX. Compared with oats, intercropping with BAV increased (P < 0.05) in vitro rate of gas production and total volatile fatty acid production, indicating a higher rate and extent of rumen degradation of BAV forage. In contrast, BIV forage harvested in June had lower (P < 0.05) rate of gas production and total volatile fatty acid production than June oats, but in general no differences in the in vitro rumen fermentation were detected between oats and BIV samples harvested in July. The results indicate that forage yield and quality can be enhanced by intercropping oats with BAV; however, intercropping with BIV increased yield but decreased nutritive value of the forage.

Ewes giving birth to female lambs produce more milk than ewes giving birth to male lambs

Abstract A total number of 23,271 parturitions were studied from two sheep farms of the Churra (CH) and Lacaune (LA) breeds. CH lambs were kept with their mothers during the first 30 days of age; from that moment onwards, ewes were machine-milked. LA lambs were not allowed to suckle their mothers, and ewes were machine-milked from parturition. Milking length (ML), total milk yield (TMY) and daily milk yield (DMY) (TMY/ML) were calculated. For the CH breed, there was an effect (p < .001) of prolificacy on ML, TMY and DMY and of offspring gender on TMY and DMY. For the LA breed, prolificacy and offspring gender had an effect (p < .001) on ML, TMY and DMY. Ewes giving birth to twin lambs produced more milk (CH: +0.15 l/d and +27.5 l/ewe; LA: +0.15 l/d and +11 l/ewe), than ewes giving birth to single lambs. For single parturitions in the CH breed, ewes giving birth to females produced more milk (+0.04 l/d and +5.2 l/ewe) (p < .0001) than ewes giving birth to males. In this breed, this effect of female offspring on milk production was similar for those ewes giving birth to twin lambs. In conclusion, ewes presenting twin parturitions produced more milk than single parturitions and the presence of female lambs had a positive effect on milk yield. These results open new possibilities to increase profitability of dairy sheep farms through a selection of the offspring gender.