In light of the exponential rise in feed costs within the livestock sector, the scientific research and valorization of novel agro-industrial by-products have essential strategies in animal nutrition. The overall objective of this study was to characterize and evaluate the inclusion of a novel olive pulp included at 12% of the concentrate on a dry matter basis in the diet of Murciano–Granadina goats to assess its effects on ruminal fermentation, nutrient digestibility, energy and nitrogen metabolism, and milk yield and composition. Two experiments were conducted, taking into account two groups (control group, CTL, and an experimental group) with the inclusion of 12% olive pulp in the concentrate (OPD): one in vivo trial in metabolic cages (n = 10 nulliparous female goats (34.1 ± 0.70 kg) per treatment) was conducted to evaluate digestibility, nitrogen balance, and energetic utilization; and a second on-farm production trial (n = 24 adult dairy goats (53.6 ± 1.14 kg) per treatment). The results showed no significant differences in energy balance or microbial protein synthesis between CTL and OPD (p > 0.05). However, the OPD exhibited higher digestibility of dry matter (71.2 vs. 68.8%; p = 0.028), organic matter (70.8 vs. 68.4%; p = 0.026), and crude fat (85.9 vs. 83.4%; p = 0.024), but lower crude protein digestibility (70.7 vs. 73.4%; p = 0.012) and nitrogen excretion (1.24 vs. 1.44 g/kg^0.75; p < 0.001). Additionally, ruminal butyrate concentrations were higher in OPD goats (13.5 vs. 11.3 mol/100 mol of total short-chain fatty acids; p = 0.020). Although milk yield remained unaffected, the OPD exhibited higher milk protein (4.17 vs. 3.79%; p = 0.036) and conjugated linoleic acid (0.620 vs. 0.400%; p < 0.001) concentrations compared to CTL. These findings demonstrate that the inclusion of 12% of the novel olive pulp in goat concentrate is a viable feeding strategy that maintains productive performance while enhancing the nutritional quality of milk.

Climate change is exerting significant negative impacts on various sectors, with livestock farming being particularly affected. One of the most pressing challenges in this context is the growing shortage in the availability of conventional fodder. This scarcity has intensified the search for alternative feed sources, with particular interest in underutilized resources often considered waste due to limited knowledge of their nutritional value. This study aimed to assess whether watermelon plant silage (WPS) could be used as a forage source in ruminants. The chemical composition of WPS and alfalfa hay (AH) was analyzed. Results showed similar protein content (21.1 vs. 18.9 g CP/100 g DM, respectively), with WPS exhibiting higher crude fat content (3.16 vs. 1.29 g/100 g DM) but lower hemicellulose (9.95 vs. 14.6 g/100 g DM) and cellulose (20.0 vs. 26.8 g/100 g DM) content compared to AH. In the first in vitro trial, WPS and AH were incubated independently to compare their fermentation behavior. WPS produced a higher concentration of short chain fatty acids (SCFA) (65.9 vs. 61.0 mM; P = 0.304), lower proportions of propionate (P = 0.001), and higher proportions of isobutyrate (P = 0.001). In a second in vitro trial, a formulated goat diet (commercial concentrate and AH in a 1:1 ratio) was used as a control to assess the impact of replacing 25% and 50% of AH with WPS. Trends towards higher value were observed in pH and CH4 concentration as AH was replaced by WPS. The study concluded that WPS could serve as a viable fodder to replace AH in conventional goat diets, simultaneously reducing agricultural waste and serving as a regenerative model for implementing circular economy strategies in affected agronomic sectors.

El uso de subproductos agroalimentarios en alimentación animal supone una oportunidad para la transición a la bioeconomía. En España, la industria del olivar genera cerca de 612.000 toneladas/año de subproductos, en su mayoría pulpa de aceituna (PA), cuyas características y composición permiten que pueda ser usada frecuentemente como biomasa para la producción de energía o como ingrediente para la obtención del aceite de orujo, entre otros. Sin embargo, su utilización dentro del sector de la nutrición animal no está del todo definida ya que es un elemento que depende de factores coyunturales como las variaciones en la cosecha de la aceituna y la volatilidad de los precios de la alimentación animal y de la energía. Este estudio evaluó el valor nutritivo de una variante de PA (parcialmente deshuesada y desecada, pero sin reextractacción) mediante el análisis de su composición nutritiva y la realización de cultivos in vitro de microorganismos ruminales para estudiar la fermentación ruminal (FR) tanto de la PA frente a otras materias primas comúnmente utilizadas en la elaboración de piensos para rumiantes, como de diferentes proporciones de incorporación de PA en un pienso comercial. La PA, a pesar de presentar una capacidad limitada para aportar nutrientes por su elevado contenido en lignina y bajo en proteína digestible, destacó por su contenido y composición en grasa. La ausencia de efectos negativos sobre la FR indicó la viabilidad de su empleo en la alimentación de rumiantes hasta en un 15 % de inclusión.

Current strategies in animal nutrition aim to reduce reliance on conventional protein sources by promoting locally available and sustainable alternatives. Retama monosperma (L.) Boiss, an endemic shrub of the Iberian Peninsula and Morocco that is adapted to harsh dune environments, has been identified as a potential novel protein feed. However, its seeds contain high levels of quinolizidine alkaloids (QA), which may limit their nutritional use. The objective of this study was to evaluate the in vivo effects of partially replacing 20% or 80% of peas with raw or heat-treated R. monosperma seeds in goat diets on feed intake, nutrient digestibility, nitrogen and energy utilization, ruminal fermentation, microbial protein synthesis, and animal health. Additionally, various aqueous-thermal treatments were evaluated to reduce QA content, with the most effective method selected for the feeding trial. The seeds showed a total QA concentration of 27,189 mg/kg, with cytisine accounting for 99.2% of the total alkaloids, along with minor amounts of N-methylcytisine and anagyrine. Detoxification efficiency varied among treatments, achieving QA reductions from 55.7% to 95.4%. In vivo results indicated that inclusion of R. monosperma seeds modified ruminal fermentation, increasing ammonia concentration and urinary purine derivatives, suggesting enhanced protein degradability and microbial protein synthesis. Despite these changes, no negative effects were observed on feed intake, apparent nutrient digestibility, nitrogen balance, or blood metabolic parameters. In conclusion, partial replacement of conventional protein sources with raw or heat-treated R. monosperma seeds appears feasible in moderate goat production systems without compromising animal performance or health.

Current strategies in animal nutrition aim to reduce reliance on conventional protein sources by promoting sustainable alternatives. Retama monosperma (L.) Boiss, an endemic shrub of the Iberian Peninsula and Morocco adapted to harsh dune environments, has been identified as a potential novel protein feed. However, its seeds contain high levels of quinolizidine alkaloids (QA), which may limit their nutritional use. This study evaluates the in vivo effects of partially replacing the conventional protein (peas) in the concentrate of goat diets with raw (20%) or heat-treated (80%) R. monosperma seeds on feed intake, nutrient digestibility, nitrogen and energy utilization, ruminal fermentation, microbial protein synthesis, and animal health. Additionally, various aqueous-thermal treatments (soaking for 24hours, drying at 50 °C-48 hours, and variations in the boiling duration and in the medium and leaching procedures) were evaluated to reduce QA content, with the most effective method selected for the feeding trial. The seeds showed a total QA concentration of 27,189mg/kg, with cytisine accounting for 99.2% of the total alkaloids. Detoxification efficiency varied among treatments, achieving QA reductions from 55.7% to 95.4%. The inclusion of retama seeds modified ruminal fermentation, increasing ammonia concentration and urinary purine derivatives, suggesting enhanced protein degradability and microbial protein synthesis. Nevertheless, no negative effects were observed on feed intake, apparent nutrient digestibility, nitrogen balance, or blood metabolic parameters. In conclusion, partial replacement of conventional protein sources with raw or heat-treated R. monosperma seeds appears feasible in moderate goat production systems without compromising animal performance or health.

The study aimed to evaluate the nutritional value of watermelon plant silage (WPS) and to assess the effect of replacing alfalfa hay (AH) with WPS in a diet formulated for dairy goats on the basis of two in vitro trials. The study used four goats as donors of rumen microbiota to analyze in vitro fermentation parameters. The chemical composition analysis revealed that WPS and AH had similar protein content (21.1 vs. 18.9 g CP/100 g DM), but WPS had lower contents of organic matter (77.4 vs. 89.6 g/100 g DM), neutral detergent fiber (36.3 vs. 49.4 g/100 g DM), acid detergent fiber (26.4 vs. 34.6 g/100 g DM), acid detergent lignin (6.40 vs. 8.01 g/100 g DM), and amino acids (716 vs. 874 g AA/kg N) compared to AH. Conversely, WPS had higher crude fat content (3.09 vs. 1.29 g/100 g DM) and different macro- and micromineral content values than AH. In a first in vitro trial, WPS and AH were incubated independently to compare their fermentation behaviour, indicating that the metabolizable energy tended to be higher for WPS compared to the AH diet (6.67 vs. 5.72 MJ/kg DM; P = 0.058). WPS fermentation produced higher concentrations of total volatile fatty acids than AH (66.6 vs. 53.3 mM; P = 0.037), lower proportions of propionate and valerate (P ≤ 0.022), higher proportions of isobutyrate (P = 0.001), and showed similar gas production (GP) kinetics, as degradation rate and its potential release, and estimated organic matter digestibility. In a second in vitro trial, a formulated goat diet (consisting of commercial concentrate and AH in a 1:1 ratio) was used as a control to assay the impact of replacing 25 and 50 % of AH by WPS. Trends were observed in several parameters, such as a linear increase in GP rate (P = 0.088), organic matter digestibility (P = 0.067), and CH4 concentration in the gas produced (P = 0.094) as AH was replaced by WPS. The study concluded that WPS could serve as a viable fodder to replace AH in conventional dairy goat diets while simultaneously reducing agricultural waste and serving as a regenerative model for implementing the circular economy strategy in the affected agronomic sectors.