Both Weaning Weight and Post-weaning Growth Performance Affect Nutrient Digestibility and Energy Utilization in Pigs

A total of 96 weanling barrows were selected to represent the 10% lightest, median, and heaviest pigs at weaning (n=30 per weaning weight category). Barrows utilized in a 27-d growth and metabolism study, where total urine and fecal grab samples were collected on d 30, 31, and 32 post-weaning. At the completion of the experiment, pigs in each weaning weight (WW) category were divided into the slowest, median, or fastest 33% average daily gain (ADG) category, yielding a nested design. The digestibility of dry matter (DM), nitrogen (N), and gross energy (GE) differed, resulting in different digestible energy (DE) and DE intakes across WW and ADG categories. Pigs with a lighter WW and slower ADG within WW had lower energy requirements for maintenance and were more efficient at converting energy into gain. Together, these data suggest that both weaning weight and post-weaning growth performance affect nutrient digestibility and utilization in nursery pigs. This research increases our understanding of nutrient use in nursery pigs, and will allow us to make more strategic dietary recommendations in the future

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

Feed Intake, Feed Efficiency, and Growth of Pigs Selected for Divergent RFI Fed High Versus Low Energy Diets

With the price of corn on the rise, producers are looking for alternative feedstuffs that would allow them to finish pigs at a cheaper price. However, this would result in feeding pigs a low energy, high fiber (LEHF) diet while pigs were selected for efficiency and growth on a high energy, low fiber (HELF) diet. The objective of this experiment was to determine if pigs from a line selected for low RFI (more efficient) on a HELF diet maintained their superiority in feed intake and efficiency to pigs selected for high RFI when fed LEHF diet. The results of this study showed that pigs from the low RFI line have greater feed efficiency than pigs from the high RFI line when fed a standard HELF diet, but this difference disappeared when they were fed a LEHF diet. Diet did not affect feed intake of the low RFI pigs but resulted in a reduction in feed intake of the high RFI linewhich resulted in both lines consuming the same amount of feed on the LEHF diet. Pigs grow slower on the LEHF diet but there was no difference between lines for either diet. The results of this study suggest that, as feed costs rise and producers look more and more towards alternative feedstuffs, selection may need to be based on performance on such diets, rather than a traditional corn-soy diet

Evaluation of Iodine Value Product and Dietary Linoleic Acid as a Predictor of Carcass Iodine Value under Commercial Conditions

A 134 d experiment housed in a commercial research barn using 1,213 pigs randomly allotted to 1 of 6 dietary treatments [choice white grease(CWG)or corn oil(COIL)included at 2, 4, and 6%]found that: dietary linoleic acid is a superior predictor of carcass iodine value(IV)than iodine value product (IVP) and dietary linoleic acid must be limited to meet carcass IVstandards. Using dietary linoleic acid to predict carcass iodine value will allow producers to meet carcass IVstandards more accurately. It can be used as a tool to enable the use of various fat sources while maintaining packer standards for carcass IV. To achieve a maximum carcass of IV of 74, total linoleic acid in the diet should not exceed 3.8% and daily linoleic acid should not exceed 88 grams

Effect of Reducing Mean Particle Sizeof Corn DDGS Using a Roller Mill or a Hammermillon Apparent Total Tract Digestibility of DM, GE, Nitrogen and NDF in Growing and Finishing Pigs

The aim of this studywas totest iffurther grinding of corn DDGS isadvantageous in terms of apparent total tract digestibility (ATTD) of DM, GE, nitrogen (N), and NDFingrowing and finishing pigs.It was also tested to determine if ATTD was different between hammermill and roller millgrinding methods.There were 3 diets. Each diet consisted of 51% corn ground at 500 microns with a roller mill, and 45% of corn DDGS ground at 450 microns using a hammermill, or 45% corn DDGS ground at 450 microns using a roller mill,or 45% of corn DDGS not further ground (unprocessed) at 650 microns.Results show thatparticle size reduction either with a roller mill or a hammermill (from 650 to 450 microns) increasedATTDof GE and DM of corn DDGS, tended to increase ATTD of N,but had no effect on ATTD of NDF. Finishing pigs had grater ATTD of GE and CP thangrowing pigs (tended to be greater for ATTD of DM). There were no effectsof growth stage in ATTD of NDF.There were no interactions betweenparticle size reduction and growth stage.In conclusion, reduction of particle size of corn DDGS (650 to 450 microns) either with a roller or with a hammermill has a beneficial effecton digestibilityof valuable dietary components in growing and finishing pigs

Irrespective of Differences in Weaning Weight, Feed Efficiency is Not Different among Pigs with Varying Average Daily Gain

A total of 120 weanling barrows were selected to represent the 10% lightest, median, and heaviest pigs at weaning (n=30 per weaning weight category). Eight pigs per weaning weight (WW) category were harvested as an initial slaughter group. The remaining 96 barrows were utilized in a 27-d growth and metabolism study, and harvested on d 33 or 34 post-weaning. At the completion of the experiment, pigs in each WW category were divided into the slowest, median, or fastest 33% average daily gain (ADG) category, yielding a nested design. Although average daily feed intake (ADFI) increased with increasing WW and ADG categories, feed efficiency (G:F) was not different. While tissue accretion rates varied due to WW and ADG category, the composition of gain was not affected. In conclusion, both WW and ADG affect the physiological development of pigs

Transitioning to net energy: A swine story

Net energy (NE) is one member of the sequence of energy systems which also includes gross energy (GE), digestible energy (DE), and metabolizable energy (ME). It is perhaps the most sophisticated because it attempts to consider more components of the ingredient or diet which normally cannot be used by the pig for maintenance and/or productive purposes. Gross energy makes no such adjustment and therefore has little direct value in diet formulation. Digestible energy corrects for energy which is lost in the feces, and metabolizable energy also adjusts for energy lost in the urine. The data in Table 1 reveal that heat increment averages 22% of gross energy, and ranges from 17 to 28%, across an array of ingredients that are frequently used in commercial pig diets. Interestingly, the range in NE is about 81%, much greater than the range in ME at 55%. At a very crude level, this suggests that NE accounts for more variation among ingredients than does ME; looked at another way, using ME to formulate diets essentially assumes that HI is similar across ingredients and does not need to be considered. Of course, this is not true

Effect of Low Energy, High Fiber Diets on Pigs Selected for Residual Feed Intake

The ever high feed costs in swine production contribute to the largest variable expense for today’s producers. Due to this fact, research has focused on increasing feed efficiency. In this study, residual feed intake (RFI) was utilized as a measure of feed efficiency in lines of purebred Yorkshire pigs that were selected for increased and decreased feed efficiency on a standard corn-soybean diet that was high in energy and low in fiber (control diet). The low RFI (LRFI) line was selected for increased feed efficiency while the high RFI (HRFI) line was selected for reduced feed efficiency. In generations 8 and 9, the low and high RFI lines were challenged with a low energy, high fiber diet (LEHF). This diet reflects the addition of alternative feed stuffs to swine diets in commercial settings in order to decrease feed costs. Results indicate that the difference in feed efficiency between the two lines was substantially lower when fed the LEHF diet compared to the control diet. Thus, when pigs are fed diets with substantial byproducts, it is important that pigs are also selected for efficiency under such diets