Influence of substituting 25% alfalfa hay with Panicum maximum cv. Mombasa with or without spirulina supplementation on the productive performance of fattening Barki lambs

Abstract

Combining salt-tolerant forages with conventional forage can provide an alternative solution for enhancing livestock production in areas affected by salt. This study aimed to evaluate the effects of substituting 25% of alfalfa hay with Panicum maximum hay, with or without Spirulina (2 mg/g), on the feed intake, digestibility, ruminal fermentation, blood parameters, and growth rate of Barki lambs. Thirty-two lambs, aged 3 months, with an average initial body weight of 21.62 kg (± 3.23), were used in the fattening experiment. The animals were weighed and then randomly assigned to four groups, eight lambs each. The experimental diets were isonitrogenous and isocaloric, containing 40% forage. Alfalfa was partially replaced with Panicum hay, with T1 and T2 having 0% Panicum and T3 and T4 containing 25%. Additionally, animals in T2 and T4 received Spirulina supplementation at 2 mg/g. The substitution of 25% of alfalfa hay with Panicum resulted in a significant reduction (p < 0.0001) in feed intake, TVFA, and NH3 levels. Lambs-fed diets containing 40% alfalfa hay demonstrated the highest nutrient digestibility (CP 790.2 vs. 765.85, EE 817.7 vs. 758.6, CF 632.90 vs. 551.60), nutritive value (TDN 741.90 vs. 711.70), blood parameters (TP 6.44 vs. 5.97, Alb 3.5 vs. 3.27), and growth rates (FBW 49.75 vs. 46.06, TG 28.12 vs. 24.44, ADG 234.37 vs. 203.) compared to those receiving diets with 10% Panicum. Supplementation with Spirulina at 2 mg/g significantly increased feed intake, TVFA (7.87 vs. 6.84), NH3(18.10 vs. 16.78) levels in the rumen, digestibility (CP 746.38 vs. 710.61, EE 812.4 vs. 763.9, CF 622.10 vs. 562.40), nutritive value (TDN 736.50 vs. 717.10), blood parameters (TP 6.34 vs. 6.07, Alb 3.49 vs. 3.32), and growth rates (FBW 49.16 vs. 46.65, TG 27.53 vs. 25.03, ADG 229.47 vs. 208.59)(p < 0.0001). In conclusion, incorporating 25% Panicum hay in lamb diets, particularly with Spirulina supplementation (2 mg/g), supports notable performance compared to pure alfalfa diets. While alfalfa remains superior, Panicum cultivation in saline lands is still viable. This combination is especially beneficial for lamb production in Egypt's desert regions.