L. W. Turner

Reducing Heat Stress in Dairy Cows Through Sprinkler and Fan Cooling

Heat stress in dairy cows can reduce both cow comfort and milk production. Sprinkler and fan cooling offers promise as means of reducing heat stress in cows. This article describes a sprinkler and fan cooling system installed at a feed bunk and evaluates system performance in a temperate, humid climate. The results indicate the system increased cow comfort and milk production during the test period.

Acute heat stress effects on heat production and respiration rate in swine

Sixteen Large White ×Landrace high-lean-growth barrows (83.5 ± 3.2 kg) were acutely exposed to one of four treatment temperatures (18, 24, 28, or 32°C) for a period of 22 h. The barrows had ad libitum access to feed and water during the experiment. During the 22 h exposure, CO2 production, O2 consumption, moisture production, feed intake and water intake were measured in an indirect calorimeter. Respiration rate was measured every 6 h by visual observation of flank movement. The calculated heat production was significantly affected by temperature and ranged from 695 to 560 kJ/(day kg0.75). Feed intake decreased at both 28°C and 32°C. Water intake increased only at 32°C. Moisture production increased slightly at 28°C; however the greatest increase was at 32°C. Respiration rate was affected by both temperature (P 0.1). The respiration rate increased exponentially with increasing temperature above 18°C.

AN OPTIMAL MISTING METHOD FOR COOLING LIVESTOCK HOUSING

ABSTRACT The stress ratio (K) used in Janssens equation for calculating grain pressure was determined for soybeans by four different methods. Static stresses were measured in a 0.91 m diameter x 2.743 m high model galvanized smooth steel bin. The four methods were: 1) measure vertical loads on the floor and wall separately; 2) measure vertical and hoop strains in the bin walls with six, two-element, rosette gages evenly spaced around the bin circumference at 15.2 cm above floor, 3) measure horizontal and shear loads at the bin wall with three ring load cells placed at different heights on the model bin wall (15.2, 61.0, and 106.7 cm above the floor); and 4) directly measure vertical and horizontal stresses within the grain mass using in-mass transducers (IMTs) at four different heights at the bin center (15.2, 61.0, 106.7, and 152.4 cm above the floor). A total of 18 replications were performed. For grain depths less than H/D = 2.8, K-ratio decreased with increasing depth of soybeans. At depths about three times the bin diameter (U/D = 3.0), the K-ratio approached a constant value that may be approximated by KQ = 1 - sin p, where p is the angle of internal friction of grain to grain.

Modeling the Physiological Growth of Swine Part I: Model Logic and Growth Concepts

This article is Part 1 in a series of three articles describing the computer model (NCPIG) that was developed to simulate the physiological growth of swine. The methods and techniques used to simulate the interaction of feed intake and the various metabolic processes for the growing swine are presented. These processes include nutrient digestion, nutrient storage in the blood, body maintenance, lean mass growth, excess fat growth, and waste and urine production. Animal heat production and thermal energy balance is described in Part 3 of this series. The model was shown to provide reasonable predictions of the empty body weights used to develop the supporting body component growth curves

Modeling the Effects of Diet Formulation on Nitrogen and Phosphorus Excretion in Swine Waste

Two weight classes of growing-finishing swine were fed corn-soybean diets lower in protein and phosphorus to determine the reduction in nitrogen (N) and phosphorus (P) in swine waste when compared to pigs fed a conventional diet. For the two weight classes, total N waste was reduced 32% and 25% while total P excretion was reduced 39% and 38%. The experimental results were used to calibrate the NCPIG model to predict N and P excretion levels. Model excretion values for the same diets showed similar trends in mineral reduction by diet, but were higher for urinary N when compared to observed values. A portion of this difference in urinary N was attributed to lower body maintenance of the experimental animals. The impact of the lower protein and phosphorus diets was evaluated over the growing-finishing period using the NCPIG model. Model results showed an approximate reduction of 44% in total N and P excretion when compared to the conventional diet with little impact in time of production. The results of this project indicate that diet manipulation is a viable tool for U.S. swine producers in maintaining a sustainable U.S. swine industry.

A body composition model for predicting beef animal growth

Abstract Two beef animal growth computer simulations were compared as to the effects of altering feed energy density. Steers of varying initial degrees of fatness were evaluated. The BEEF-NC114 model used NRC regression equations to predict growth while the BEEF-S156 model used physiological age and body components. Otherwise, the models were essentially identical. On average, the predictions of both models were reasonably close to each other. However, the BEEF-S156 model was more sensitive to extreme conditions of high or low nutrition.

ECONOMIC EVALUATION OF MISTING-COOLING SYSTEMS FOR GROWING/FINISHING SWINE THROUGH MODELING

The economics of investing in a misting-cooling system for growing-finishing swine [20-107 kg, (44-236 lb)] were evaluated for central Kentucky summer environments using the NC-204 swine growth model (Bridges et al., 1992a,b; Usry et al., 1992). The economic returns to misting were compared for different weather years (1995 and 1983) and two initial starting dates of 15 June and 5 July. The results of the simulation model found that for all instances the use of a misting-cooling system reduced the time of growth to market and produced a pig with less backfat. Depending on the potential for evaporative cooling in the weather year and the starting date in the facility, the economic returns for the misting-cooling system varied from

Modeling the Physiological Growth of Swine Part III: Heat Production and Interaction With Environment

0.49 per pig in 1995 to

GI TRACT SIMULATION MODEL OF THE GROWING PIG

3.40 per pig in 1983.

Automated Weighing of Group-housed, Growing-finishing Swine

Part 3 of this series presents the development and validation of the relationships used in the NCPIG computer model to simulate heat production and interaction with the thermal environment of growing swine. The model was developed to simulate transient, diurnal energy flows for growing pigs considering metabolic heat production, sensible and radiant heat gains and losses, latent heat losses and heat storage within the animal body. The relationships used in the model are described and the results of comparisons between predicted heat production and observed data for individually housed pigs are presented. The predicted and observed data were for crossbred gilts ranging in weight from 30-100 kg and for three levels of environmental temperature: lower critical temperature (LCT), LCT+58 C, and LCT-58 C. The simulated heat production values for the LCT experiment were within the observed mean minus one standard deviation while those for the LCT+5 and LCT-5 treatments were approximately one standard deviation above and below their respective means.