The increasing pressure of abolishing and/or decreasing the use of antibiotics as antimicrobial growth promoters for livestock calls for alternative solutions to sustain the efficiency of current livestock production. Among the alternatives, essential oils have a great potential and are generally considered natural, less toxic, and free from residues. Essential oils have been proven in numerous in vitro studies to exert antimicrobial effects on various pathogens. The current review touched on the basics of essential oils, and the in vivo effects of essential oils on growth, intestinal microflora, anti-oxidation, immune functionality, meat qualities as well as the possible modes of action in poultry and pigs, and the future research areas were proposed.

Phosphorus (P) is an essential nutrient for diverse biological processes, which aggregate to the animal's requirement for P, and nutritionists strive to meet this requirement accurately. The P demand for a growing pig comprises requirements for maintenance and tissue deposition. The P in feed ingredients, however, must be digested and absorbed before its ultimate partition between the 2 aforementioned requirement components. Phosphorus from various sources could behave differently during digestion and absorption, which results in their disparate bioavailability for pigs. The system of standardized total tract digestibility reflects true total tract digestibility of P and feed ingredient effects on specific endogenous P loss with relative ease of implementation, and this system guarantees satisfactory additivity in digestible P among the ingredients in a diet—the foundation for diet formulation. The basal endogenous P loss, which is much easier to measure than the specific endogenous P loss, is considered as part of the pig's maintenance requirement. With this arrangement, a digestibility framework is established both for measuring the P-providing capacity of various feed ingredients and for describing the pig's P requirement. This framework entails basic understanding of the function, digestion, absorption, excretion, and homeostasis of P as support pillars. Understanding the workings of this framework enables potential integration of factors such as environment conditions and disease status in future P requirement models. The current review discusses dietary sources, digestion, absorption, bioavailability and requirement of P for growing pigs to understand the status quo, revealing the points of consensus as well as those of debate, and to encourage further investigation to provide more clarity.

Two experiments were conducted to investigate the efficacy of benzoic acid on the growth performance of nursery and grower-finisher pigs. A randomized complete block design was used in both experiments with the initial body weight as the blocking factor. There were 3 treatments corresponding to 3 dietary levels of benzoic acid: 0, 0.3%, and 0.5%. In experiment 1, a total of 144 PIC L1050 barrows (initial body weight 7.1 ± 0.6 kg) were used with each treatment replicated 8 times. In experiment 2, a total of 288 PIC L1050 barrows (initial body weight 36.1 ± 3.6 kg) were used with each treatment replicated 16 times. There were 6 barrows in each replicate pen for both experiments. Experiments 1 and 2 lasted 28 and 70 days, respectively. In experiment 1, average daily gain (ADG) of all growth phases increased linearly (P < 0.05) with increasing supplementation of benzoic acid, which led to a linear improvement in average body weight on d 28 (P < 0.05). There was also an improvement in feed conversion ratio (FCR) of d 0 to 14 (linear effect: P < 0.05) and in average daily feed intake (ADFI) of d 14 to 28 and d 0 to 28 (linear effect: P < 0.01). In experiment 2, ADG during d 0 to 35 and d 35 to 70 and average body weight on d 35 improved linearly (P < 0.05) with increasing supplementation of benzoic acid. Average daily gain of d 0 to 70 and average body weight on d 70 increased significantly in a both linear and quadratic manner. There was a linear improvement in FCR in all growth phases (P < 0.05). In conclusion, the dietary inclusion of benzoic acid at the supplementation levels of 0.3% and 0.5% significantly improved the growth performance of nursery and grower-finisher pigs in the current study; the nursery pigs responded to the dietary supplementation of benzoic acid up to 0.5% linearly while the grower-finisher pigs achieved the optimal ADG at the calculated supplementation level of 0.36%.

Introduction: Copper is an essential trace element crucial for enzyme synthesis and metabolism. Adequate copper levels are beneficial for maintaining the normal immune function of the spleen. Copper deficiency disrupts the metabolic processes within the spleen and impairs its immune function. This research examines the impact of copper deficiency on the spleen and the potential recovery following copper supplementation. Methods: Weaned mice underwent a 4-week copper-deficient diet, succeeded by 1-week of copper repletion via intraperitoneal copper sulfate injection. Histological examination was used to assess pathological changes in the spleen. Biochemical assays were performed to measure oxidative stress levels in the spleen. ELISA, qPCR, and Western blot were employed to examine alterations in inflammatory markers, immune indicators, and oxidative regulatory factors across various levels. Results: Copper deficiency caused histological damage to the spleen, altered the expression of oxidative stress regulatory pathways (Nrf2, Keap1, and HO-1), and affected the expression of key inflammatory enzymes (iNOS, COX2) and transcription factor NF-κB, leading to oxidative damage. This was reflected by decreased levels of SOD, GSH, and T-AOC, along with increased levels of CAT and MDA. The levels of inflammatory cytokines IL-1β, TNF-α, IL-6, and IL-8 were notably increased. Copper supplementation significantly improved these changes. Conclusions: Copper deficiency leads to spleen tissue damage in mice, affecting the Nrf2 regulatory pathway and inducing oxidative damage. Subsequent copper supplementation with copper sulfate effectively ameliorates the damage caused by copper deficiency.

Three independent trials were conducted to evaluate the efficacy of a novel phytase in laying hens. Trial 1 used a total of 90 laying hens (Lohmann Brown, 33-wk-old) fed either a negative control (NC) diet with 0.09% non-phytate P (NPP) or NC supplemented with 187.5 or 375 FYT phytase/kg feed for 4 d before collection of excreta and ileal digesta to measure ileal digestibility and retention of Ca and P. In trial 2 and 3, a total of 108 laying hens (Hy Line Brown, 25-wk-old) and 360 hens (Lohman Brown, 25-wk-old) were used, respectively. In both trials, the hens were randomly assigned to 3 dietary treatments: NC with 0.1% NPP, positive control (PC) and NC plus 187.5 FYT phytase/kg feed, the experimental diets were fed for 12 wk, and egg production and bone mineralization were measured. The results showed that the ileal digestibility of P increased both linearly (P = 0.012) and quadratically (P = 0.01) with increasing supplementation of phytase in trial 1. In trial 2, phytase supplementation significantly improved egg production, egg weight, and feed conversion ratio and reduced the percentage of broken eggs during the overall trial duration compared with NC. In trial 3, phytase significantly improved egg production, egg weight, and feed intake and reduced the percentage of broken eggs during the entire trial duration. In addition, percentage and weight of bone Ca and P increased significantly with added phytase. In trial 2 and 3, there was no significant difference between PC and the phytase treatment. In conclusion, the novel phytase significantly increased the ileal digestibility of P in a short-term digestibility study and improved egg production and bone mineralization in a 12-wk laying cycle. Ileal digestibility of P rather than P retention in short-term digestibility studies as well as egg production and whole tibia mineralization in long-term studies should be measured to demonstrate the efficacy of phytase in laying hens.

The objective of this study was to measure apparent total tract digestibility (ATTD) of Ca and P as well as reproductive performance in late-gestation and lactating sows supplemented with a novel phytase and to compare the response to phytase supplementation between late-gestation and lactating sows. Forty-five late-gestation sows and 45 lactating sows were used in experiments 1 and 2, respectively, in a completely randomized design. The sows were provided with a control diet or the control diet supplemented with 187.5 or 375 FYT phytase/kg feed for 10 days. The diets were prepared according to the formulas in use for production but without any inorganic P supplement. Titanium dioxide was included at 3 g/kg feed as an indigestible marker. Each dietary treatment was replicated with 15 sows individually-housed in farrowing stalls. The sows were allowed to adapt to the experimental diets for 5 days before a 5-d fecal collection by grab sampling, and the performance of the sows and their litters were measured until weaning. The results showed that the ATTD of Ca increased linearly (P < 0.001) while the ATTD of P increased both linearly and quadratically (P < 0.01) with increasing supplementation of phytase in both late-gestation and lactating sows. There was no significant effect of phytase on the ATTD of dry matter, crude protein, and gross energy, and the performance of the sows and their progenies. The phytase added at 187.5 and 375 FYT/kg feed released 0.07% and 0.10% digested P, respectively, in late-gestation sows, which compared with 0.09% and 0.12% digested P in lactating sows. In conclusion, a novel phytase at 187.5 to 375 FYT/kg feed could release 0.07 to 0.12% digestible P for sows. It appeared that using the P digestibility values of feed ingredients listed by NRC (2012) to formulate a diet for sows might overestimate dietary P supply and a greater response to phytase supplementation could be expected in lactating sows than in late-gestation sows.