Mokhtar Mahouachi

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 effect of spineless cactus (Opuntia ficus-indica f. inermis) supplementation on growth, carcass, meat quality and fatty acid composition of male goat kids.

The objective of this study was to determine the effects of grain compared to spineless cactus feeding on goat kids growth, carcass characteristics and FA profile. For this purpose, 21 kids were used and allocated to 3 groups receiving a low quantity (200g) of oat hay. The control group received ad libitum a concentrate containing 130g crude protein (CP) per kg of dry matter (C130). The second group received half of that contained consumed by the control one but its CP content was 260g/kg DM and spineless cactus ad libitum (C260-Cac). In the third group, concentrate intake was limited to soya bean at a quantity that provided the same CP quantity as the two other groups and also cached spineless cactus was distributed ad libitum (Soya-Cac). Animals of all groups had free access to water. At the end of the growth trial which lasted for 74 days, all kids were slaughtered. Samples of longissimus dorsi muscle were used for meat quality and FA composition study. Animals in the control group and those in the C260-Cac had higher growth rate than Soya-Cac diet animals. Muscle and adipose tissue mean weights were higher in the first groups while the bone weight was similar in all treatments. Animals given Soya-Cac diet had relatively less fat (10.5%) than those fed other diets (p<0.001). Carcass fat content tended to be lower (p=0.07) in C260-Cac goats (13.5%) than in those of the C130 group (15.8%). The ultimate pH ranged between 6.18 and 6.48; it was higher in meat from control goats (C130) than in animals receiving cactus. Dietary treatment had no significant effect (p>0.05) on meat moisture, ash, crude fat and protein contents. The intra muscular lipid composition in fatty acids showed differences between the control group and those receiving cactus. Cactus in the diet was associated with more C18:2 and conjugated linoleic acid (CLA) as well as a higher proportion of PUFA and PUFA:SFA ratio than control ones. In conclusion, this study showed that cactus feeding of goat kids maximises the proportion of CLA, PUFA and PUFA:SFA ratio.

Effects of feeding system and nitrogen source on lamb growth, meat characteristics and fatty acid composition.

For this study, 28 lambs were allocated to four groups: two groups were raised in stalls and fed a hay-concentrate ration. The two remaining groups were reared on dry pasture and received concentrate in stalls. In each feeding system, two iso-nitrogen concentrates were used, soya bean and soya plus faba bean. At the end of the growth trial (77 days), all lambs were slaughtered. Samples of longissimus dorsi muscle were used for muscle analysis and fatty acid (FA) composition determination. Average daily gain (134g) was similar for all treatments. Stall lambs deposited significantly (p<0.001) more fat per day (13 vs 5g) and slightly more muscle (41 vs 35g) than pasture grazing ones; the first had more fat tissue (5.2kg) than the later (4.6kg). All these parameters were not influenced by nitrogen source. FA profile and meat characteristics were similar for all dietary treatments. It could be concluded that dry pasture did not affect meat quality but lead to the leaner lambs.

Effects of the nature of nitrogen supplementation on voluntary intake, rumen parameters and ruminal degradation of dry matter in sheep fed oat silage-based diets

The effects of nature of nitrogen supplementation on silage DM intake (SDMI), total DM intake (TDMI), rumen parameters and ruminal degradation of DM of silage and wheat straw were studied using four adult Noire de Thibar rams. Silage was made from predominantly oats harvested at milk stage and ensiled without preservative. The silage was offered ad libitum as the sole diet (OS) or supplemented with 450 g DM of iso-nitrogen (25.6 g/kg DM) and iso-energy (0.8 Unite Fourragere Lait: UFL/kg DM) concentrate containing soybean meal (SBM), urea (UR) or poultry litter (PL) as nitrogen supplements. SDMI (g/kg W 0.75 × day) and TDMI (g/kg W 0.75 × day) were affected ( P< 0.001) by the type of supplement and averaged 63.9, 60.1, 54.9, 51.1 and 63.9, 81.4, 74.8, 72.2 for OS, SBM, PL and UR diets, respectively. In comparison with other diets, SBM diet systematically decreased ( P< 0.05) the pH of the rumen after the morning feeding and reduced the rumen concentration of total VFA at 1 h after feeding. SBM diet decreased DM disappearance of the oat silage incubated in nylon bags for 72 h ( P< 0.05), but not of wheat straw. The three supplements increased the ammonia-N concentrations in the rumen for several hours after feeding in comparison with the OS diet. However, only the SBM diet kept this difference just before the next meal. It is concluded that despite its low nutritive value (0.62 UFL and 108 g crude protein/kg DM), the oat silage is well consumed by the local ruminants accustomed to use poor forages for a long time. In Tunisia, poultry litter may be used as a nitrogen source to supplement the oat silage for sheep.

Effects of restricted feeding and re-feeding of Barbarine lambs: carcass composition and fatty acid composition

Fifty intact male Barbarine lambs were used to assess the effects of restricted feeding and re-alimentation on carcass composition and fatty acid (FA) composition of intramuscular fat. Five lambs were slaughtered at the start of the trial; the remainder were randomly allocated to three groups. One group was offered only stubble grazing (low : L), another, also on stubble, received, indoors, an average of 80 g dry matter (DM) of soya-bean meal per day (medium : M); the third group was kept indoor and had free access to hay and 450 g of concentrate (high : H). At the end of this restriction period (70 days), five lambs per group were slaughtered. The 10 remaining animals in each group were divided into two groups receiving concentrate and hay ad libitum. The crude protein (CP) content of the concentrate was 160 and 210 g/kg DM in the two treatments, respectively. At the end of the trial all animals were slaughtered at 37·61 ± 2·05 kg live weight. In the restriction period, bone tissue was similar in terms of mass for all diet treatments. The absolute weight of muscle and fat in carcasses was higher for unrestricted sheep ( H) than for restricted ones, but L and M lambs had proportionately less fat and more muscle than those given food indoors. Intramuscular fat composition was similar for all the treatments. During this period, the carcass gain of M lambs had the highest proportion of muscle and the lowest fat concentration, which is the better composition. At the end of the compensating period, all carcasses contained the same quantity of bone and muscle, but unrestricted sheep had significantly more fat than compensating ones. So, carcasses of compensating animals contained relatively less fat (240 v. 310 g/kg) and more muscle (550 v. 500 g/kg) than unrestricted ones. The carcass gain of lambs with an earlier nutritional history on L had the highest muscle and the lowest fat concentration. The intramuscular lipid composition in terms of fatty acids showed differences between treatments. Unrestricted animals contained more C14 : 0 and C16 : 0 and compensating animals more C18 : 2 and a higher proportion of polyunsaturated fatty acids ( PUFA) and PUFA : saturated FA ratio. There were no significant differences associated with CP level during the re-alimentation period

Effects of finishing lambs in rich aromatic plant pasture or in feedlot on growth and meat quality

A total of 21 fat-tail Barbarine lambs were divided into three groups. Two groups were conducted on feedlot (FL). The daily diet was oat hay and 800 g of concentrate/lamb for control feedlot group (CFL) and control plus 200 g of aromatic plant (AP) of pasture for the second group (APFL). The last group was conducted on a natural pasture (NPG – natural pasture grazing group) rich with APs; sheep received daily 400 g/lamb of the same concentrate. At the end of the experiment, 70 days, all lambs were slaughtered. The average daily gain was 161 ± 11 g, and the slaughter body weight was 43 kg for all groups. Also, daily muscle and fat gains were similar for all groups. The initial pH was significantly higher for NPG than for both the FL ones. The use of AP increased a* and b* values for both rearing modes (16.4 vs. 15.5 and 7.3 vs. 5.8, respectively) but lightness value only for NPG group (L* = 37.3). Meat from NPG and APFL groups was more tender than that of FL one. However, meat juiciness was lower for grazing than for both the FL groups. In conclusion, with the half quantity of concentrate grazing natural pasture system resulted in the same growth rate as FL. The use of APs in natural pasture or in FL system leads to the same growth rate and tends to improve carcass traits. Furthermore, this use resulted in an increase in meat tenderness and lightness.