Diet modifications to improve finishing pig growth performance and pork quality attributes during periods of heat stress1,2

Abstract

A total of 196 barrows (88 kg) were used in a 2 x 2 factorial arrangement of treatments and housed in a facility (seven pigs per pen) where temperatures cycled between 27 and 35 degrees C. Treatments consisted of (as-fed basis) two CP levels (13.6 or 11.3%) and two levels of added fat (1 or 8%). Diets were formulated to the same true digestible lysine:ME ratio (1.68 g of lysine/Mcal of ME). Diets were fed and growth variables were measured until pigs reached 114 kg of BW. Ham and LM (loin) 24-h pH (PH24), and light reflectance (CIE L*, and a*, and b*, and hue angle) were taken after slaughter. Additionally, loins were removed and measured for i.m. fat, moisture, glycolytic potential, and subjected to a 7-d retail display evaluation that measured pH, light reflectance, and subjective color and odor score. The remaining boneless lumbar loin segment was vacuum-sealed for 14 d and subsequently measured for pH, light reflectance, and color. Pigs fed the high-CP, low-fat diet had a lower ADG than all other treatments (P = 0.06). High-fat feeding resulted in improved ADG (CP x Fat; P = 0.06) and G:F (Fat effect; P < 0.01). Higher fat and lower protein levels both increased final BF (P = 0.07). Pigs fed the low-CP diets had lower ham PH24 (P < 0.01). Loin PH24 was higher with high fat feeding (P = 0.10). Additionally, pigs fed high fat diets had lower L* values on the ham face and cut loin 24 h after slaughter (Fat effect; P <or= 0.02). These loin color differences were maintained through the 7-d retail display and 14-d storage period. There were no differences in loin i.m. fat or moisture content; however, high-fat feeding tended to decrease loin glycolytic potential (P = 0.11). These results suggest that in a hot environment, decreased CP content improved finishing pig ADG when dietary fat supplementation was low. High dietary fat inclusion during heat stress improved ADG and G:F, especially when CP level was elevated. High-fat diets fed in a hot environment increased pork color intensity by decreasing the glycolytic potential at slaughter and elevating muscle pH.

Reduction in the protein level and addition of oil in diets for finishing pugs under different temperatures

“…In the present study, effect of crude protein only occurred (P<0.05) in diets with 4.5% oil, regardless of the temperature. These results were similar to Spencer et al (2005), who observed higher fat thickness in animals fed diets containing lower crude protein and higher inclusion level of soybean oil. These results may be related to the higher value of net energy provided by low crude protein diets containing amino acid addition, coupled with the effect of extra caloric oil.…”

“…In the case of diets with reduced crude protein, this effect cannot be shown due to a greater amount of free amino acids and a lower protein diet, while in the warm environment, the lower feed intake may have limited this effect. Spencer et al (2005) found improvement in feed conversion of animals kept in the heat when receiving diets with 8% of soybean oil. According to the authors, this is due to the lowest caloric increment generated by the oil in the diets.…”

“…Ambient temperature influenced only (P<0.05) loss by cooling. Orlando et al (2007) and Trindade Neto et al (2008) Kerr et al (1995) and Tuitoek et al (1997) reported that reducing the level of crude protein in the diet increased the amount of energy available for tissue deposition and favored the production of fatter carcasses at slaughter. In the present study, effect of crude protein only occurred (P<0.05) in diets with 4.5% oil, regardless of the temperature.…”

Evaluating equations estimating change in swine feed intake during heat and cold stress1

“…The biological influence of heat stress is impacted by duration of exposure to extreme temperatures (Renaudeau et al, 2007), night cooling (Xin and DeShazer, 1991;Patience et al, 2005), relative humidity (Huynh et al, 2005), diet composition (Jørgensen et al, 1996;Kerr et al, 2003), and genetics (Brown-Brandl et al, 2001;Sutherland et al, 2006), among others. In particular, ME content (Baldwin and Sainz, 1995;Rodrigues et al, 2012), protein and AA balance (Kerr et al, 2003;Spencer et al, 2005;Wolp et al, 2012), dietary additives (Zier-Rush et al, 2014) ,and mineral concentrations (Haydon et al, 1990;Kim et al, 2009) all affect responses to heat stress. To understand the relationships among variables, a mixed-effect linear model of absolute intake was also derived from the data set.…”

Unsaturated to Saturated Fatty Acids Ratio Adjustmentin Diets on Digestibility and Performance of Growing Pigs

“…Park et al (2012) noted that dietary fat plays a considerable role in the development of growing-finishing pigs because of its high energy content. Moreover, it is recommended for use in growingfinishing pigs being reared under environmental heat stress due to a lower heat increment than other feedstuff (Spencer et al, 2005). Jung et al (2003) found that the replacement of animal fat with vegetable oil rich in unsaturated fatty acids, such as soybean oil or corn oil, resulted in an improved growth performance in weaning pigs.…”