This review examines several molecular mechanisms underpinning oxidative stress in ruminants and their effects on blood and milk oxidative traits. We also investigate strategies to alleviate or repair oxidative damages by improving animal immune functions using novel feed additives. Microbial pathogenic cells, feeding management, and body condition score were some of the studied factors, inducing oxidative stress in ruminants. The predominance of Streptococcus spp. (24.22%), Acinetobacter spp. (21.37%), Romboutsia spp. (4.99%), Turicibacter spp., (2.64%), Stenotrophomonas spp. (2.33%), and Enterococcus spp. (1.86%) was found in the microbiome of mastitis cows with a decrease of d-mannose and increase of xanthine:guanine ratio when Streptococcus increased. Diversity of energy sources favoring the growth of Fusobacterium make it a keystone taxon contributing to metritis. Ruminal volatile fatty acids rose with high-concentrate diets that decreased the ruminal pH, causing a lysis of rumen microbes and release of endotoxins. Moreover, lipopolysaccharide (LPS) concentration, malondialdehyde (MDA), and superoxide dismutase (SOD) activities increased in high concentrate cows accompanied by a reduction of total antioxidant capacity (T-AOC), glutathione peroxidase (GPx), and catalase (CAT) activity. In addition, albumin and paraoxonase concentrations were inversely related to oxidative stress and contributed to the protection of low-density and high-density lipoproteins against lipid peroxidation, protein carbonyl, and lactoperoxidase. High concentrate diets increased the expression of MAPK pro-inflammatory genes and decreased the expression of antioxidant genes and proteins in mammary epithelial tissues. The expression levels of NrF2, NQO1, MT1E, UGT1A1, MGST3, and MT1A were downregulated, whereas NF-kB was upregulated with a high-grain or high concentrate diet. Amino-acids, vitamins, trace elements, and plant extracts have shown promising results through enhancing immune functions and repairing damaged cells exposed to oxidative stress. Further studies comparing the long-term effect of synthetic feed additives and natural plant additives on animal health and physiology remain to be investigated.

Rumen protozoa prey on feed-degrading bacteria synthesizing microbial protein, lowering nitrogen utilization efficiency in ruminants. In this in vitro study, we evaluated six plants (Adansonia digitata, Flemingia macrophylla, Kalimeris indica,Brassica rapa subsp. chinensis, Portulaca oleracea, and Calotropis gigantea) for their potential to inhibit rumen protozoa and identified the phytochemicals potentially responsible for protozoa inhibition. Rumen protozoa were anaerobically cultured in vitro in the presence of each plant at four doses. All of the tested plants reduced total rumen protozoa (p ≤ 0.05), but C. gigantea and B. rapa were the most inhibitory, inhibiting rumen protozoa by 45.6 and 65.7%, respectively, at the dose of 1.1 mg/mL. Scanning electron microscopy revealed a disruption of the extracellular structure of protozoa cells. Only C. gigantea also decreased the wasteful ammoniagenesis (p ≤ 0.05). Moreover, the A. digitata extract inhibited α-glucosidase activity by about 70% at 100 µg/mL. Reversed-phase high-performance liquid chromatography analysis detected quercetin, anthraquinone, 3-hydroxybenzoic acid, astragaloside, and myricetin in the tested plant leaves. These plants may hold potential as feed additives to reduce rumen protozoa and α- glucosidase activity. Future research is needed to identify the specific anti-protozoal compound(s), the effects on the rumen microbiome, and its fermentation characteristics.

The present study was carried out from June to November 2014 in Obout and Ntoung areas, in the centre and east regions of Cameroon, respectively. Its aim was to determine the socio-economic contribution of the traditional exploitation of the African palm weevil grub (Rhynchophorus phoenicis) to livelihoods. One hundred and three grub collectors from eight different villages were surveyed. Furthermore, field observations were done both in the swampy raffia forests and in the villages. Results show that two methods of grub exploitation coexist in the study area: the traditional gathering with an average productivity of 35±13.2 grubs per trunk and the semi-farming system with an average productivity of 50±10.1 grubs per trunk. The daily productivity per collector varies between 389 grubs (3.59 kg) and 570 grubs (5.27 kg). Palm weevil grubs are used for food, traditional medicine, and income. Daily income from the trade of these resources varies between 15,560 Central African CFA franc (XAF) and 22,800 XAF. Therefore, professional grub collectors can reach a maximum monthly income of 456,000 XAF, contributing to 78% of the household revenue. Nevertheless, harvesting methods are very destructive to the ecosystem, as a single collector can cut down an average of 1,120 raffia trunks in the harvesting process.

This study aimed at evaluating the milk production after supplementing Calotropis gigantea (Giant milkweed, GM) silage as a new functional feed additive for ruminants. Cows refused to eat GM plant and we processed it into silage before feeding. After ensiling, six ruminally cannulated dairy cows were assigned to two treatment groups (GM silage supplementation treatment and control without GM silage supplementation) in a cross over design. Repeated sampling of milk and rumen fluid was done the last days of the third and fourth week after treatment. Ensiling GM increased the crude proteins, neutral detergent fiber and acid detergent fiber while ash was unchanged. There was completely no dry matter intake (DMI) when supplementing GM forage to the cows meanwhile, DMI and milk yield returned to normal conditions but feed efficiency, milk protein, milk fat and lactose slightly increased when supplementing GM silage. Rumen protozoa genera such as Entodinium, Ophryoscolex, Eudiplodinium, Dasytricha and Isotricha were maintained. A dose effect study remained to be carried out to identify an effective dose that could bring significant enhancement of the animal production after supplementing GM silage. This study revealed that the silage form of GM can be a new source of proteins for dairy cows and an appropriate dose could potentially induce some improvement of the milk production and composition. Therefore, the plant will not continue to be perceived as an invasive weed but as a new forage to be integrated to the cow’s diet.