Dietary Supplementation with Conjugated Linoleic Acid (CLA) on Production, Health and Culling Parameters in Transitioning Holstein Cows

Lactating Holstein cows were assigned to one of three dietary CLA treatments. Study objectives were to determine the effects of a protected (lipid-encapsulated tran-10, cis- 12) CLA on milk production, health and culling frequency, reproduction and overall feasibility in large commercial dairy operations. Results indicate that CLA is capable of inducing milk fat depression (MFD) within 15 d following parturition and the reduced milk energy output likely indicates an improved energetic status. However, feeding CLA had no effect on other productions, metabolic, health, or culling variables

Effects of Heat Stress on Ovarian Physiology in Growing Pigs

Ovaries were obtained from growing pigs that had been heat-stressed and were evaluated for alterations in a signaling pathway known to play a critical role in ovarian physiology. Our results indicate that hyperthermia alters this pathway in a short space of time (after 7 days). Identifying how and why heat stress alters ovarian physiology are important in developing therapeutic approaches to prevent the reduction in reproductive performance associated with warm summer months

Does Heat Stress Alter the Pig’s Response to Dietary Fat Source, as it Relates to Apparent or True Total Track Digestibility?

Heat stress affects a plethora of pork production variables, in part stemming from a reduction of feed intake. The experimental objective was to investigate the effect of heat stress on the pig’s response to dietary fat in terms of growth performance and digestibility over a 35 d finishing period. A total of 96 barrows were randomly allotted to 1 of 9 treatments arranged as a 3 × 3 factorial with the main effects of environment [thermonetural (TN), pair-fed thermoneutral (PFTN), or heat stress (HS)] and diet [a corn-soybean meal based diet with 0% added fat (CNTR), or the CNTRL with 3% added tallow (3%TAL), or 3% added corn oil (3%CO)]. Pigs were individually housed to record intake. Fecal samples were collected on d 17 (~ 114 kg). No significant interactions between environment and diet were observed (P \u3e 0.100). HS decreased ADFI (27.8%; P\u3c 0.001), ADG (HS = 0.72, TN = 1.03, PFTN = 0.78 kg/d; P \u3c 0.001), and G:F (HS = 0.290, TN = 0.301, PFTN = 0.319; P = 0.006). G:F but not ADG or ADFI tended to increase with added fat (CNTR = 0.292, 3%TAL = 0.303, 3%CO = 0.314 g/100 g; P ≤ 0.073). Environment had no impact of TTTD of AEE (P = 0.118). In summary, HS decreased ADFI, ADG, G:F and ATTD of AEE, but had no significant impact on TTTD of AEE. Therefore, the pig’s response to dietary fat source is not different in heat stress conditions as compared to thermoneutral conditions

Effects of Heat Stress and Plane of Nutrition on Production and Metabolism in Growing Pigs

We heat-stressed growing pigs and evaluated the differential effects of environmental hyperthermia and reduced feed intake. Our results indicate that hyperthermia directly effects production and metabolism and many of these are independent of reduced nutrient intake. Identifying how and why heat stress alters metabolism and physiology are prerequisites in developing ameliorating strategies to prevent the reduction in performance and lost income typically observed during the warm summer months

Climate Dependent Heat Stress Mitigation Modeling for Dairy Cattle Housing

Dairy cattle are susceptible to heat stress with reported milk production loss exceeding 1.2 billion dollars in 2010. Heat stress occurs when the local thermal environment prevents adequate dissipation of metabolic heat production over extended periods. Implementing mitigation strategies in order to reduce heat stress has been a crucial need as dairy housing has transitioned from pasture to indoor housing systems. In order to maximize production, producers need the most effective cooling system to reduce heat stress. A heat stress mitigation model was developed using TMY3 data sets as inputs. The objectives of this research were to: (i) analyze the thermal environment’s ability to reduce heat stress in dairy cattle in selected regions using TMY3 data, (ii) model Holstein cattle subjected to various environmental modification systems (elevated airspeed, evaporative pad cooling, direct sprinkling) by region, (iii) create a universal barn/cooling system model to apply to selected regions with given TMY3 data inputs, and (iv) develop contour maps with optimal cooling system recommendations throughout the United States. A transient thermal balance model was developed using equations and parameters from published heat stress models in order to quantify heat dissipation from a dairy cow to her environment. The model was initially tested and evaluated using two TMY3 stations (Fresno, California SN:723890 and Eau Claire, Wisconsin SN:726435). The model’s predictions were within one standard deviation of field data. Once validated, the model was applied to all 215 TMY3 Class 1 stations and contour maps of the U.S. were created for producers to determine which cooling strategy is the most economical in their region

Heat stress adaptations in pigs

Implications • Heat stress is a global issue constraining animal agriculture productivity, negatively affects welfare, and reduces production efficiency in many countries. • The effects of heat stress on pig production will intensify, if climate change continues as predicted. • To date, modifying the environment is the most effective way to mitigate the effects of heat stress. • Identifying additional strategies (nutritional and genetics) to maximize pork production during the warm summer months is necessary to satiate a growing demand for high quality meat for human consumption

Short-term exposure to heat stress attenuates appetite and intestinal integrity in growing pigs 1

Acute heat stress (HS) and heat stroke can be detrimental to the health, well-being, and performance of mammals such as swine. Therefore, our objective was to chronologically characterize how a growing pig perceives and initially copes with a severe heat load. Crossbred gilts (n=32; 63.8±2.9 kg) were subjected to HS conditions (37°C and 40% humidity) with ad libitum intake for 0, 2, 4, or 6 h (n=8/time point). Rectal temperature (Tr), respiration rates (RR), and feed intake were determined every 2 h. Pigs were euthanized at each time point and fresh ileum and colon samples were mounted into modified Ussing chambers to assess ex vivo intestinal integrity and function. Transepithelial electrical resistance (TER) and fluorescein isothiocyanate-labeled dextran (FD4) permeability were assessed. As expected, Tr increased linearly over time (P\u3c0.001) with the highest temperature observed at 6 h of HS. Compared to the 0-h thermal-neutral (TN) pigs, RR increased (230%; P\u3c0.001) in the first 2 h and remained elevated over the 6 h of HS (P\u3c0.05). Feed intake was dramatically reduced due to HS and this corresponded with significant changes in plasma glucose, ghrelin, and glucose-dependent insulinotropic peptide (P\u3c0.050). At as early as 2 h of HS, ileum TER linearly decreased (P\u3c0.01), while FD4 linearly increased with time (P\u3c0.05). Colon TER and FD4 changed due to HS in quadratic responses over time (P=0.050) similar to the ileum but were less pronounced. In response to HS, ileum and colon heat shock protein (HSP) 70 mRNA and protein abundance increased linearly over time (P\u3c0.050). Altogether, these data indicated that a short duration of HS (2-6 h) compromised feed intake and intestinal integrity in growing pigs

Determining the Effectiveness of Microbial Protease on Production Variables in Lactating Holstein Cows

Lactating Holstein cows were assigned to a control diet or a diet containing a blend of supplemental protease enzymes (Rumagentin™, Feed Sources LLC, Alta Loma CA) at the Iowa State University Dairy farm. Study objectives were to examine the effects of proteases on milk yield, milk composition, feed intake and feed efficiency in lactating Holstein cows. Our results indicate that protease enzymes enhanced feed conversion efficiency and nitrogen utilization of dairy cows

Metabolic and hormonal acclimation to heat stress in domesticated ruminants

Environmentally induced periods of heat stress decrease productivity with devastating economic consequences to global animal agriculture. Acclimatization is a process by which animals adapt to environmental conditions and engage behavioral, hormonal and metabolic changes that are characteristics of either acclimatory homeostasis or homeorhetic mechanisms used by the animals to survive in a new ‘physiological state’. These physiological modifications alter nutrient partitioning and may prevent heat-stressed lactating cows from recruiting glucose-sparing mechanisms. How these metabolic changes are initiated and regulated is not known. A better understanding of the adaptations enlisted by ruminants during heat stress is necessary to enhance the likelihood of developing strategies to simultaneously improve heat tolerance and increase productivity. Periodo prolungati di stress da caldo severo inducono effetti negative sulla produzione con conseguenze devastanti sulla economia del comparto agro-zootecnico. L’acclimatamento è un processo attraverso cui gli animali si adattano alla variazione delle condizioni ambientali modificando il loro comportamento e variano l’equilibrio ormonale e metabolico con meccanismi di tipo sia omeostatico sia omeoretico con lo scopo di sopravvivere alle nuove condizioni raggiungendo un nuovo stato fisiologico. Queste modificazioni fisiologiche alterano la ripartizione dei nutrienti e possono essere responsabili di una maggiore e diverso utilizzo del glucosio. Come queste variazioni e adattamenti metabolici hanno inizio non è ancora ben noto. Una migliore comprensione dei meccanismi di adattamento dei ruminanti alle condizioni di stress da caldo, permetterà di sviluppare strategie per contemporaneamente migliorare la termo tolleranza e la produttività di soggetti esposti a condizioni stressanti

Effects of In-utero Heat Stress on Porcine Post-natal Thermoregulation

Pigs were exposed to heat stress (HS) and thermoneutral (TN) conditions in-utero. Post-natally, they were exposed to either TN or HS environments for 15 days, and differences in physiological response comparing inutero treatment groups were determined. Our results indicated that gestational HS (GHS) pigs had increased core body temperature during post-natal HS compared to pigs exposed to gestational TN (GTN); however, there were no production differences between gestational groups. This provides evidence suggesting pigs exposed to in-utero HS may have an increased tolerance to post-natal HS, at least from a productivity standpoint