Can conventional forages be replaced with cotton plant (Gossypium hirsutum) wastes in fattening lambs? Laboratory and animal studies.

The cotton plant (Gossypium hirsutum) is a shrub native to many arid and semi-arid regions around the world, while the nutritional value of its wastes has been less scientifically investigated. Different components of whole cotton plant wastes (WCPW) including leaf blade, cotton pod, stem, root, bract, petiole, and cottonseed were evaluated for their nutritional values by standard laboratory methods. After that, we tested the WCPW for partial substitution (0, 20, 40, and 60% substitution or 0, 10, 20, and 30% of dietary dry matter (DM)) with dietary common forage in a completely randomized design with 32 feedlot male lambs for 90 days. A diverse range of chemical and mineral compositions was found among the different WCPW's components. The cottonseed had the highest crude protein (CP) and ether extract (EE) contents, while the lowest neutral detergent fiber (NDF) and acid detergent fiber (ADF) were observed in the leaf blade (P < 0.0001). The highest contents of calcium, phosphorus, sodium, magnesium, and iron were also observed in the leaf blade (P < 0.0001). Higher potential gas production, in vitro organic matter digestibility (OMD), in vitro dry matter digestibility (DMD), and total volatile fatty acids (TVFA) were also related to the leaf blade (P < 0.0001). Bract had the highest acid-base buffering capacity (P < 0.0001). The lambs fed on 30% of dietary DM with WCPW exhibited lower final body weight (BW), average daily gain (ADG), CP or NDF digestibility, ruminal TVFA, propionate, plasma total protein, and higher feed conversion ratio (FCR) compared to the control group. Generally, WCPW can be substituted up to 40% of common forages (or 20% of diet DM) without any adverse effect on growth performance and blood metabolites of feedlot lambs, especially during feed shortages.

A study on the nutritional characteristics of some plants and their effects on ruminal microbial fermentation and protozoa population.

We designed this project to determine the nutritional potential and ruminal microbial fermentation properties of eight rangeland plants (Dracocephalum moldavica L., Melissa officinalis L., Ruta graveolens L., Perovskia abrotanoides Kar., Cichorium intybus L., Borago officinalis L., Peganum harmala L., and Teucrium polium L.) collected from the semi-arid region of Iran at two consecutive years (2019 and 2020) for ruminant diets. Medicago sativa as a common forage was also considered as control. We determined the chemical-mineral composition, buffering capacity, in vitro gas yield, ruminal fermentation, and protozoa population in a culture medium with the standard laboratory methods. A significant difference in chemical-mineral compounds was observed among the studied plants (p < 0.05). A lower crude protein range (6.28% for Cichorium intybus L. to 18.4% for Melissa officinalis L.) was observed rather than Medicago sativa (20.3%). The amount of calcium was highest in Peganum harmala L. (23.5-24.2 g/kg DM) and lowest in Ruta graveolens L. (1.15-1.25 g/kg DM). Dracocephalum moldavica L. exhibited the highest acid-base buffering capacity (235-242 mEq×10-3) among other plants. The highest decrease in total protozoa and other protozoan populations was observed when Perovskia abrotanoides Kar. was added to the culture medium. Teucrium Polium L. had the greatest potential gas yield and its total volatile fatty acid was comparable with Medicago sativa. It seems that eight plants are nutritionally suitable for partial replacement of the conventional plants such as Medicago sativa in diets of small ruminants, however dietary supplementation of Peganum harmala L. due to its alkaloids content should be done with caution.