-Two experiments were conducted using lactating Friesian-Holstein cows to measure the effects of heat stress, using temperature-humidity index (THI), on milk production, milk composition and dry matter intake (DMI) under the Mediterranean climate. These trials were carried out in two periods differing in average THI values (68 ± 3.75 vs. 78 ± 3.23 for the spring and summer periods, respectively). Daily THI was negatively correlated to milk yield (r = -0.76) and feed intake (r = -0.24). When the THI value increased from 68 to 78, milk production decreased by 21% and DMI by 9.6%. Milk yield decreased by 0.41 kg per cow per day for each point increase in the THI values above 69. Milk fat (3.24 vs. 3.58%) and milk protein (2.88 vs. 2.96%) were lower for the summer group. THI was positively correlated to respiration rate (RR) (r = 0.89), heart rate (HR) (r = 0.88), rectal temperature (RT) (r = 0.85) and cortisol (0.31), and negatively with free thyroxin (-0.43). As the THI values increased from 68 to 78, RT increased by 0.5 o C, HR by 6 beats, and RR by 5 inspirations per min. The average concentration of cortisol increased from 21.75 to 23.5 nmol·L -1 (P > 0.05), while that of free thyroxin decreased from 15.5 to 14.5 pmol·L -1 , (P > 0.05). Summer heat stress reduced milk yield and DMI, altered milk composition and affected the physiological functions of confined lactating Holstein cows managed under Mediterranean climatic conditions. dairy cow / temperature-humidity index / milk production / intake / physiology Résumé -Relation entre l'index température-humidité et la production laitière chez la vache Frisonne élevée sous un climat méditerranéen. Deux essais ont été menés sur des vaches laitières Frisonne-Holstein pour étudier l'effet du stress thermique sur la production et la composition du lait et sur l'ingestion de la matière sèche sous un climat méditerranéen. Ces essais ont été réalisés en deux périodes qui diffèrent seulement par leurs valeurs d'index température-humidité (THI) (68 ± 3,75 et 78 ± 3,23 pour le printemps et l'été, respectivement). Le THI journalier est négativement corrélé à la production laitière (r = -0,76) et à l'ingestion (r = -0,24). Lorsque la valeur THI est passée de 68 à 78, la production laitière a diminué de 21 % et la matière sèche ingérée de 9,6 %. Pour chaque unité d'augmentation du THI au delà de 69, la production laitière chute de 0,41 kg par vache par jour. Les teneurs du lait en matière grasse (3,24 et 3,58 %) et en protéines (2,88 et 2,96 %) étaient plus faibles (P < 0,05) pendant la période estivale. Le THI est positivement corrélé à la température rectale (r = 0,89), aux rythmes cardiaque (r = 0,88) et respiratoire (r = 0,85) et au cortisol (r = 0,31), mais né-gativement avec la thyroxine libre (r = -0,43). La variation de la valeur THI de 68 à 78 a engendré une augmentation de la température rectale, de la fréquence cardiaque et du rythme respiratoire de 0,5 o C, 6 battements par min et 5 inspirations par min, respectivement. La concentration plasmatique moyenne ...

No abstract

Increased demand for ethanol as a fuel additive has resulted in dramatic growth in ethanol production. Ethanol is produced from corn by either wet milling or dry-grind processing. In wet milling, the corn kernel is fractionated into different components, resulting in several coproducts. Wet-milling plants are capital intensive because of equipment requirements; they produce large volumes of ethanol and are corporate owned. In dry-grind processing, the corn kernel is not fractionated and only one coproduct, distillers' dried grains with solubles (DDGS), is generated. Dry-grind plants require less equipment and capital than wet mills. They generate smaller volumes of ethanol, are producer owned, and add direct benefits to rural economies. Most of the increase in ethanol production during the past decade is attributed to growth in the dry-grind industry. The marketing of coproducts provides income to offset processing costs. For dry-grind plants, this is especially important, because only one coproduct is available. Several issues could affect DDGS marketing. The increasing volume of DDGS accompanying ethanol production could reduce market value; high phosphorous content could limit the use of DDGS, because of animal waste disposal issues. Water removal is a costly processing step and affects the economics of ethanol processing. Technologies to remove germ and fiber from DDGS could produce a new coproduct suitable for feeding to nonruminants; this would expand the markets for DDGS. Reducing phosphorus in DDGS would sustain markets for conventional DDGS. The development of more efficient methods of water removal would increase the efficiency of ethanol processing and reduce the costs of processing. New technologies could contribute to greater stability of dry-grind plants.

Cereal Chem. 82(2):187-190 Three different modified dry-grind corn processes, quick germ (QG), quick germ and quick fiber (QGQF), and enzymatic milling (E-Mill) were compared with the conventional dry-grind corn process for fermentation characteristics and distillers dried grains with solubles (DDGS) composition. Significant effects were observed on fermentation characteristics and DDGS composition with these modified dry-grind processes. The QG, QGQF, and E-Mill processes increased ethanol concentration by 8-27% relative to the conventional dry-grind process. These process modifications reduced the fiber content of DDGS from 11 to 2% and increased the protein content of DDGS from 28 to 58%.

The effect of dilution rate (D) on carbohydrate, fibrous and nonfibrous, and protein fermentation by ruminal microorganisms was studied using a single-effluent continuous-culture system. The diets of fibrous carbohydrate, nonfibrous carbohydrate, or protein were formulated with soybean hulls (FC), ground corn (NFC), or isolated soy protein (PR) as the primary ingredient, respectively. Six dilution rates (.025, .050, .075, .10, .15, and .20/h of fermenter volume) were used. Digestibilities of DM, OM, and CP for the three diets and of NDF and ADF for the FC diet decreased (P<.001) as D increased, although the response of the digestibility to D varied with diet. Increasing D resulted in an increase in pH (P<.001) and a decrease (P<.001) in ammonia concentration. Daily volatile fatty acid production increased (quadratic; P<.01) for the FC and NFC diets, but decreased (quadratic; P<.001) for the PR diet. Increasing D quadratically increased (P<.001) the molar percentage of acetate and propionate, but quadratically decreased (P<.001) butyrate and valerate for the FC and NFC diets. For the PR diet, the molar percentage of propionate and valerate increased (quadratic; P<.01), whereas acetate and butyrate decreased (linear; P<.001) in response to increasing D. Molar percentage of isobutyrate and isovalerate decreased (P<.01) with increasing D for all three diets. As D increased, daily microbial N production showed quadratic responses with maximum values achieved at .126, .143, and .187/h D for the FC, NFC, and PR diet, respectively. There was a positive correlation between microbial growth efficiency (MOEFF) and D. A quadratic model fit the data of MOEFF as affected by D, and maximum MOEFF of 37.3, 59.6, and 71.4 g of bacterial N/kg OM truly fermented were calculated to be achieved at .177, .314, and .207/h D for the FC, NFC, and PR diet, respectively. Dilution rate significantly influenced the ruminal microbial fermentation of fibrous and nonfibrous carbohydrates and proteins, and was positively related to microbial yield and growth efficiency. In addition, microbial nitrogen composition, and therefore efficiency, was affected by substrate fermented.