The Impact of Dietary Analyzed Calcium to Phosphorus Ratios and Standardized Total Tract Digestible Phosphorus to Net Energy Ratios on Growth Performance, Bone, and Carcass Characteristics of Pigs

A total of 2,184 pigs (PIC 337 × 1050; initially 27.3 lb) were used to evaluate the effects of feeding varying analyzed calcium to phosphorus (Ca:P) ratios at two levels of standardized total tract digestible (STTD) P:NE. Pens of pigs (26 pigs per pen) were assigned to 6 dietary treatments in a randomized complete block design with 14 pens per treatment. Diets consisted of two levels of STTD P:NE, including the PIC recommendation (1.8, 1.62, 1.43, 1.25, 1.10, and 0.99 g STTD P/Mcal NE from 25 to 50, 50 to 90, 90 to 130, 130 to 180, 180 to 230, and 230 to 280 lb, respectively); or 75% of the PIC recommendation, and 3 analyzed Ca:P ratios: 0.90:1, 1.30:1, and 1.75:1. Diets were corn-soybean meal-based and contained phytase (Quantum Blue G, AB Vista, Marlborough, Wiltshire, UK); 500 to 210 FTU/kg with release values from 0.13 to 0.07% STTD P. There was a Ca:P × STTD P:NE interaction (P \u3c 0.05) observed for average daily gain (ADG), feed efficiency (F/G), and final body weight (BW). For ADG and final BW, when feeding 75% of PIC STTD P recommendation, increasing the analyzed Ca:P ratio decreased ADG and final BW (linear, P \u3c 0.001). However, when feeding the PIC STTD P recommendation, increasing the analyzed Ca:P ratio tended to improve ADG and final BW (linear, P \u3c 0.10). For F/G, when feeding 75% of the PIC STTD P recommendation, increasing the analyzed Ca:P ratio tended to worsen F/G (linear, P \u3c 0.10), whereas in pigs fed diets that met PIC STTD P recommendations, increasing the analyzed Ca:P ratio tended to improve F/G in a quadratic (P \u3c 0.10) manner. Despite the interactions, pigs fed the PIC STTD P recommendations had increased ADG, final BW, and improved F/G compared to pigs fed 75% of PIC STTD P recommendations (P \u3c 0.001). In summary, pigs fed at PIC STTD P recommendations had improved overall ADG and F/G compared to pigs fed diets at 75% of PIC STTD P recommendations. Additionally, increasing the analyzed Ca:P ratio worsened ADG and F/G when STTD P was below PIC recommendations but had marginal impacts when adequate STTD P was fed

Diurnally Entrained Anticipatory Behavior in Archaea

By sensing changes in one or few environmental factors biological systems can anticipate future changes in multiple factors over a wide range of time scales (daily to seasonal). This anticipatory behavior is important to the fitness of diverse species, and in context of the diurnal cycle it is overall typical of eukaryotes and some photoautotrophic bacteria but is yet to be observed in archaea. Here, we report the first observation of light-dark (LD)-entrained diurnal oscillatory transcription in up to 12% of all genes of a halophilic archaeon Halobacterium salinarum NRC-1. Significantly, the diurnally entrained transcription was observed under constant darkness after removal of the LD stimulus (free-running rhythms). The memory of diurnal entrainment was also associated with the synchronization of oxic and anoxic physiologies to the LD cycle. Our results suggest that under nutrient limited conditions halophilic archaea take advantage of the causal influence of sunlight (via temperature) on O2 diffusivity in a closed hypersaline environment to streamline their physiology and operate oxically during nighttime and anoxically during daytime