Changing patterns of human resource use and food consumption have profoundly impacted the Earth's biosphere. Until now, no individual taxa have been suggested as distinct and characteristic new morphospecies representing this change. Here we show that the domestic broiler chicken is one such potential marker. Human-directed changes in breeding, diet and farming practices demonstrate at least a doubling in body size from the late medieval period to the present in domesticated chickens, and an up to fivefold increase in body mass since the mid-twentieth century. Moreover, the skeletal morphology, pathology, bone geochemistry and genetics of modern broilers are demonstrably different to those of their ancestors. Physical and numerical changes to chickens in the second half of the twentieth century, i.e. during the putative Anthropocene Epoch, have been the most dramatic, with large increases in individual bird growth rate and population sizes. Broiler chickens, now unable to survive without human intervention, have a combined mass exceeding that of all other birds on Earth; this novel morphotype symbolizes the unprecedented human reconfiguration of the Earth's biosphere.

Figure 1. A: Major plate tectonic features of Central America. Names of principle plates are in bold and underlined. SOAM-South America, CARIB-Caribbean, SPDB-South Panama deformed belt, NPDB-North Panama deformed belt, CCRDB-Central Costa Rica deformed belt, PPB-paleoplate boundary, RJ-ridge jump. Inset shows location of B. Major tectonic features are compiled from Mackay and Moore (1990), Silver et al. (1990), Meschede et al. (1998), Barckhausen et al. (2000), and Marshall et al. (2000). Modern plate motion relative to Caribbean is from DeMets et al. (1990) and Protti et al. (1995). Small numbers give age of Cocos seafloor. B: Generalized geologic map of Costa Rica, bathymetry of Cocos plate and location of study area on Península de Nicoya (inset). FSG, Fisher seamount group; QP, Quepos Plateau; CR, Cocos Ridge. Geologic units: Nicoya Complex, random dash pattern; active arc volcanic rocks, random double-dash pattern; extinct-arc volcanic rocks, stipple pattern; Cretaceous and Cenozoic fluvial to marine clastic and volcaniclastic rocks, horizontal line pattern. Bathymetric data are from von Huene and Fluh (1994). Magnetic anomolies are from Barckhausen et al. (2000). Contour interval is 100 m, bold, and labeled every 1 km. Black dot with surrounding hachured area shows epicenter and aftershock extent of March 25, 1990, Golfo de Nicoya subduction earthquake (Mw ‫؍‬ 7.0, depth ‫؍‬ 20 km) and associated focal mechanism (Protti et al., 1995).

Work was undertaken to investigate the potential use of housefly (Musca domestica) larvae reared on broiler manure as a source of nutrition for poultry production in the United Kingdom. Nutritional analysis showed that larvae have a high (>45% dry wt.) protein content and a favorable amino acid profile that is rich in key amino acids, such as lysine and methionine. A broiler digestibility trial was carried out to determine the apparent ileal digestibility coefficients (AIDC) and true ileal digestibility coefficients (TIDC) of amino acids (AA) from insect larval meal (ILM) from M. domestica and fishmeal (FM) in broiler chickens. This was calculated using multiple linear regression technique based upon 3 inclusions of each protein source in a semisynthetic diet. One-hundred-forty-four day-old male (Ross 308) broilers were fed from hatch on a commercial starter diet for 20 days. Experimental diets were fed from d 21 to 28, and feed intakes were measured daily. On d 28, the trial was terminated, ileal digesta were collected for the determination of AIDC and TIDC of AA, and inflammatory responses (gizzard erosion and eye discharge) were measured. No significant differences were observed in digestibilities between protein sources for any AA. Furthermore, ILM feeding did not induce gizzard erosion or eye discharge at any inclusion. These results provide strong evidence to suggest that ILM of the common housefly can provide a successful alternative protein source to FM in broiler diets.

The G-protein coupled receptors (GPCRs) superfamily comprise similar proteins arranged into families or classes thus making it one of the largest in the mammalian genome.

There is little consensus as to the most appropriate methodology for the measurement of gastrointestinal pH in chickens. An experiment was conducted to establish the optimum sampling method for the determination of broiler digesta pH in birds fed differing levels of dietary calcium. Ross 308 broilers (n = 60) were fed 1 of 2 experimental diets, one containing 0.8% monocalcium phosphate and 2% limestone and one containing 0.4% monocalcium phosphate and 1% limestone. Four factors were investigated to determine the most appropriate method of measuring broiler gastrointestinal digesta pH: removal from the tract, prolonged air exposure, altering the temperature of the assay, and controlling the water content of the digesta. The conditions were assessed at bird ages from 7 to 42 d posthatch. Dietary Ca content had no significant effect on in situ pH, but it contributed toward variance in ex situ pH of both gizzard and duodenum digesta. Digesta pH read higher when the digesta was removed from the tract, but the amount of time the digesta was exposed to air did not affect the reading. Digesta pH read higher when measured at room temperature than when measured at 41°C; temperature made the strongest unique contribution to explaining variance in duodenum pH, and the second strongest contribution to explaining variance in gizzard pH, after diet. When water was added to the digesta, before pH determination, the pH of the digesta read higher (P < 0.001) than when measured in situ. The method that resulted in pH readings that were most representative of bird gastrointestinal environment was insertion of a pH probe directly into the gut lumen posteuthanasia, because measurement ex situ likely encourages dissociation of carbonic acid, the major buffer in the gastrointestinal tract, which causes pH to read to be higher than when measured in situ. This study shows that the method of pH measurement needs careful consideration to ensure the validity of the result.