M. Rekik

The effect of nutrition prior to and during mating on ovulation rate, reproductive wastage, and lambing rate in three sheep breeds

Abstract The effects of moderate (M) and high (H) levels of nutrition prior to and during mating were evaluated according to the reproductive performance of 46 Queue Fine de l’Ouest (QFO), 45 D’Man and 40 D ’ Man × QFO ewes. For 6 weeks prior to synchronised mating and 3 weeks thereafter, ewes in M treatment were given a diet providing, proportionately, 1.0 for QFO and D ’ Man × QFO and 1.5 for the D’Man of the estimated metabolizable energy (ME) requirements for maintenance. Ewes in H treatment were fed a daily diet providing 1.6 for the QFO and D ’ Man × QFO ewes and 2.2 for D’Man ewes of the ME requirements for maintenance. Live-weight change was recorded and reproductive performance measured from the cyclic ovarian activity (COA) and corpora lutea (CL) counts at the induced oestrus as well as the incidence of lambing and the number of lambs born. Neither breed nor the nutritional level significantly influenced the magnitude of live-weight changes between the start of the experimental nutritional treatments and the start of the mating period, a time at which 94–100% of ewes in all treatment groups were found to be cycling. At the induced oestrus, ovulation rate (OR) averaged 1.57 per ewe and a positive response of OR to improved nutrition was recorded in the prolific D’Man breed (2.26 in H ewes versus 1.78 in M ewes; P

The cactus effect: an alternative to the lupin effect for increasing ovulation rate in sheep reared in semi‐arid regions?

The present study evaluated the effects of supplementation with cactus cladodes on follicular dynamics and ovulatory response of sheep reared in semi-arid areas. A total of 76 ewes were distributed into two equal groups supplemented with either concentrated feed or cactus cladodes. After 30 days of supplementation, no differences were found between feeding regimens on the final live weight (LW; 41.5 ± 0.6 and 42.1 ± 0.7 kg in the Concentrate and Cactus groups respectively) and body condition score (BCS; 1.8 ± 0.3 and 1.8 ± 0.4 for Concentrate and Cactus group respectively). Moreover, no differences were found between the initial and the final values of both LW and BCS; thus, there were no effects of supplementation on any of both parameters. Analysis of follicular population showed that, during the follicular phase induced by ram effect, the number of follicles reaching ovulatory size increased in both groups. However, the number was always higher in Cactus ewes and, at oestrus, Cactus ewes had 1.6 ± 0.2 and Concentrate sheep had 1.2 ± 0.2 large follicles (p < 0.05). Thereafter, ovulation rate was affected by duration of supplementation; being higher in sheep fed with cactus for 6-10 days (1.7 ± 0.1) than in ewes supplied with cactus for more than 11 days (1.3 ± 0.1; p < 0.05), in sheep fed with concentrate for 6-10 days (1.2 ± 0.1; p < 0.01) and even than in individuals subjected to classical flushing with concentrate (1.3 ± 0.1; p < 0.05).

Differences in preovulatory follicle dynamics and timing of preovulatory LH surge affect fertility of maiden sheep reared in semi-arid extensive conditions

In the current study follicular dynamics, pituitary function, ovulatory response and luteal activity of 30 maiden Barbarine sheep were analyzed according to oestrus occurrence and lambing outcome after oestrus synchronisation with cloprostenol. Animals were retrospectively classified in three groups named as O- (n=7, ewes not displaying oestrus), O+L- (n=7, ewes showing oestrus but failing to lamb) and O+L+ (n=16; ewes showing oestrus and lambing thereafter). All the sheep ovulated and daily transrectal ultrasonographies revealed that preovulatory follicles were present at cloprostenol injection in all the animals. In sheep O+L+ and O+L-, 50% and 57% of the ovulatory follicles were the largest follicles at cloprostenol treatment (mean size of 4.1+/-0.26 mm and 4.3+/-0.74 mm, respectively). In O- ewes, the same percentage was higher (86%, P<0.05 when compared to group O+L+; mean size of 4.0+/-0.46 mm). The number of large follicles and the final diameter of the ovulatory follicles at oestrous tended thereafter to be higher in group O+L+ (1.4+/-0.1 and 6.4+/-0.2) than in groups O+L- (1+/-0.2 and 5.7+/-0.36) and O- (0.9+/-0.2 and 5.9+/-0.5, respectively). Conversely, the number of medium follicles at oestrus detection was higher in the group O+L- (2.1+/-0.3, P<0.05) than in the other two groups (1+/-0.2 and 1+/-0.3 for O+L+ and O- respectively). Timing of preovulatory LH surge was earlier for ewes O- (24.0+/-4.75, P<0.05) than for sheep O+L+ and O+L- (37.9+/-2.45 h and 38.0+/-4.75 h, respectively) and 94% of O+L+ ewes had a LH surge between 16 h and 64 h after cloprostenol injection compared to 57% in O+L- and O- groups (P<0.05). Thus, maiden Barbarine sheep failing to display oestrus or conceive showed alterations in their follicular dynamics and, thereafter, pituitary function and ovulatory response.

Effect of Pre-Mating Water Deprivation on Ovarian Activity and on Reproductive Traits of Mature Barbarine Ewes during Summer Season

mature Barbarine ewes were used to study the effect of water deprivation on feed intake and reproductive traits. Animals were allocated to two groups of 30 animals each. Control ewes (C) had free access to water while deprived ewes (D) were watered every 3 days during 8 weeks in mating period.Feed and water intake were recorded daily for each animal. Body weight was measured every week. Rectal temperature was also measured every week of the trial on the 1 st , 2 nd and the 3 rd day of water deprivation. Ovulation rate was determined by endoscopy 12 days after oestrus behaviour. Lambing rate and litter size were calculated. Body weight and feed intake were not affected (P>0.05) by water deprivation. However water intake increase in deprived ewes (P<0.01). Reproductive results showed that water deprivation did not affect significantly either the percentage of females in oestrus during the 3 days following ram introduction nor the return rate (80% vs 90% and 13% vs 10% respectively for control and water deprivation groups). Moreover ovulation rate, fertility and litter size were similar for both groups (110% vs 130%, 93.3% vs 100% and 103% vs 123% respectively for control and water deprivation groups). These results indicate the wide adaptation of Barbarine sheep for water deprivation as indicated by the absence of significant negative effects on reproductive performances.

Effect of water deprivation during pregnancy and lactation of Barbarine ewes on mammary secretions and lamb’s growth

The effect of water restriction was assessed in Barbarine ewes raised under extremely dry conditions. In Experiment 1, 24 adult ewes were divided into two groups balanced for age and weight. Control ewes (C) had free access to water while deprived ewes (D) were ad libitum watered every 3 days during the last 10 days of pregnancy and the first 60 days of suckling. Accumulated colostrum at birth and rate of secretion between 0-2, 2-15 and 15-24 h were not affected. C ewes yielded more milk than D ewes on days 30 and 60postpartum (1,487.38 ± 436.44 vs. 1,096.6 ± 282.85 g/24 h and 983.42 ± 228.80 vs. 639.19 ± 256.92 g/24 h respectively; P 0.05). Daily growth rates were 184.67 ± 55.98 and 162 ± 43.50 g between d 10 and d 30, and 190.60 ± 53.47 and 173.8 ± 45.75 g between d 30 and d 60 for respectively C and D lambs (P > 0.05). In Experiment 2, 24 adult ewes were allotted to treatments C and D as above except that for D ewes, water restriction started from 50 days before lambing up to 60 days postpartum. Accumulated colostrum at birth and rate of secretion between 0-2, 2-15 and 15-24 h were not affected. However, milk production was highly affected (P < 0.01) by the regime being significantly lower for D ewes at 10, 30 and 45 days postpartum. Despite differences in milk production, there was no effect of access to water of the dams on the weights and growth rates of their offsprings. At birth, C and D lambs weighed 3.4 and 3.3 kg respectively, and at day 60 corresponding figures were 11.2 and 10.3 kg. Both experiments showed an effect of water deprivation only on milk production which is not reflected in lamb weights at birth even when the ewes are deprived during the last third of pregnancy. Lamb growth after birth was also not modified. These results stress the adaptive traits of the Barbarine and should be considered while managing watering of flocks under desert conditions.

Global Warming and Livestock in Dry Areas: Expected Impacts, Adaptation and Mitigation

In most developing countries livestock is the key asset for rural people providing multiple economic, social and risk management functions. Rangelands contribute to the livelihoods of over 800 million people including poor smallholders. The arid area of the globe is home for extensive livestock production mainly based on small ruminants (Ben Salem & Smith, 2008). The most important sheared characteristic of such zones, despite the high variety of biotopes, is aridity with a very erratic pattern of rainfall and extended periods of high temperatures. These two factors together with a higher frequency of extreme climatic events will be amplified under the perspective of global warming thus affecting negatively food availability through the seasons of the year. The impacts that climate change will bring about are expected to exacerbate the vulnerability of livestock systems and to reinforce existing factors that are simultaneously affecting livestock production systems such as rapid population and economic growth, increased demand for food and products, and increased conflicts over scarce resources (e.g. land tenure, water, and feed). There is an urgent need for detailed assessment of climate change impacts in each production system and for identifying appropriate options that can help livestock keepers adapt to climate change. This chapter summarizes current knowledge on global warming, discusses its impacts on the different components of the production systems and reports technical options to overcome negative effects of climate change on the livestock productivity and health and sustainability of livestock-based production systems. The approach recommended to transfer and adopt these options is also discussed.