Search

A replicated factorial experiment using 183 individually fed crossbred barrows was conducted. The pigs were fed an 18.5% CP (.95% lysine) diet with 3,594 kcal of ME/kg. The effects of five genotypes (GT): 1) Hampshire (H) × (H × Duroc [D]), 2) synthetic terminal sire line, 3) (H × D) × (Landrace [L] × [Yorkshire (Y) × D]), 4) L × (Y × D), and 5) Y × L; two levels of ractopamine (RAC) treatment: 0 and 20 ppm; and three treatment weight periods (WT): 1) 59 to 100, 2) 73 to 114, and 3) 86 to 127 kg live weight on ADG of dissected lean (ADLG) and fat standardized lean adjusted to 10% fat content (ADSLG) and feed efficiency of ADLG (LFE) and ADSLG (SLFE) were evaluated. Initial carcass lean quantity of each individual animal was determined by a regression equation (R2= .95) generated from 30 additional barrows (six per GT) slaughtered at 59 kg and 30 (six per GT) untreated pigs slaughtered at 100 kg average live weight. Logarithmic and reciprocal transformations of dependent variables were used to stabilize heterogeneous variances and to improve normality of the residuals. Ractopamine increased (P< .0001) ADLG, ADSLG, LFE, and SLFE, respectively, by 19.5, 25.0, 19.6, and 25.5%. Differences (P< .001) were observed among genotypes for all traits, showing that considerable variation existed in the data and indicating that genetic improvement can be realized through the identification and selection of superior genotypes. For ADLG and ADSLG, a RAC × GT interaction (P< .05) was observed, demonstrating greater responses to RAC in leaner genotypes. Pigs achieved greatest lean growth rate in the 73 to 114-kg period among the three growth phases and likely reached a plateau in lean growth rate at 70 to 90 kg. Lean feed efficiency declined as BW increased. These results clearly indicate that greater benefits can be expected if pigs from leaner genotypes are treated with ractopamine and slaughtered at or before 114 kg live weight.

A replicated factorial experiment using 183 individually fed crossbred barrows was conducted. Pigs were fed an 18.5% CP (.95% lysine) diet with 3,594 kcal of ME/kg. The effects of five genotypes (GT): 1) Hampshire (H) × (H × Duroc [D]), 2) synthetic terminal sire line, 3) (H × D) × (Landrace [L] × [Yorkshire (Y) × D]), 4) L × (Y × D), and 5) Y × L; two levels of ractopamine (RAC) treatment: 0 and 20 ppm; and three treatment weight periods (WT): 1) 59 to 100, 2) 73 to 114, and, 3) 86 to 127 kg live weight on growth performance and carcass traits were evaluated. Ractopamine increased (P< .0001) amount (FSL) and percentage (PFSL) of carcass lean standardized to 10% fat content, loin eye area (LEA), and dressing percentage (PDRES) and reduced (P< .01) amount (DF) and percentage (PDF) of dissected fat. Magnitudes of RAC effects were smaller than those reported by other researchers. Effects of GT and WT on all growth and carcass traits were highly significant (P< .001) except for those of WT on ADG (P< .05) and GT on average feed intake (AFI) and backfat thickness at the last rib (BFLR; P< .05). Genotype 3 performed better for most economically important traits than did GT 1 and 4, suggesting that heterosis existed in GT 3, which essentially was obtained by crossing GT 1 and 4. Among the three treatment periods, WT 2 had the highest ADG. As BW increased from WT 1 to 3, AFI and AFI/ADG ratio (FCR) increased and lean percentage decreased. No significant interactions among RAC, GT, and WT were observed for ADG, FCR, and muscle quantity traits, indicating that the effects of RAC, GT, and WT were additive for these traits.

Three hundred sixty-one market-weight barrow and gilt carcasses were physically dissected into bone, skin, fat and muscle. A three-variable multiple linear regression equation containing the same independent variables (warm carcass weight, 10th rib loin muscle area and 10th rib fat depth) used (U.S.) to determine pork carcass lean weight was found to be the most practical means for predicting weight of muscle standardized to 10% fat. Multiple linear regression equations containing more than three independent variables produced only slight improvements in R2values; however, the standard deviation about the regression line was not greatly improved by the addition of more independent variables to this three-independent-variable regression model. A single multiple linear regression equation using the three independent variables above may not be adequate to describe variation over the entire live-weight range for all hogs marketed in the U. S. For most accurate muscle weight prediction, different equations should be used for weight subclasses with one equation for carcasses under 100 kg and another for those heavier than 100 kg. A single prediction equation for muscle weight was adequate for carcasses of both barrows and gilts.

On-line techniques for estimating carcass composition and value with potential for eventual application in the packing industry must be accurate, rapid, dependable in a plant environment and cost-efficient. Several potential technologies are discussed and data are presented to establish the relative accuracy of real-time ultrasound imaging, electromagnetic scanning and optical electronic fat-lean probes. Market-weight barrows and gilts were subjected to ultrasound image analysis prior to slaughter. Carcasses were evaluated for composition using electromagnetic scanning, ultrasound image analysis, optical probe analysis and direct measurement of loin muscle area and fat depth with a dot grid and ruler. Carcasses were fabricated into standard U.S. primal cuts and each cut was dissected into lean, fat, bone and skin. Multiple linear regression analyses to predict weight of total dissected carcass lean revealed that the electronic signal from the electromagnetic scanner, carcass length and temperature combined gave an R2of .89 (RSD 1.74). Carcass ultrasound images of fat depth and loin muscle area at the 10th rib and warm carcass weight gave an R2of .79 (RSD 2.20). The electronic probe for fat and muscle depth at the 10th rib of chilled carcasses and chilled carcass weight gave an R2of .79 (RSD 2.19). The R2is .81 (RSD 2.07) when actual loin muscle area and fat depth were determined by direct measurement in ribbed carcasses and combined with carcass weight.

AbstractThe Parkes radio telescope was commissioned in 1961, with an anticipated operational life of 15 years. Twentyfive years later the telescope has been refurbished with the aim of extending its life yet another decade or two. A major undertaking has been the complete replacement of the drive and control System. This presentation outlines the main features of the new System and its effect on the observing facilities offered at the observatory.

Eighty barrows were used in a 2 × 2 × 4 factorial experiment to examine the effects of genetic line (Hampshire × Yorkshire, H × Y, and Yorkshire × Landrace, Y × L), somatotropin (dose, 0 and 5 mg/d) and energy intake (ad libitum, 93%, 86% and 80%) on growth performance and energy requirements for lean gain over the finishing phase of growth. Four diets were formulated to maintain equal intakes of protein, vitamins and minerals at different energy intakes. Somatotropin increased growth rate 30 to 35% across diets despite an 8 to 12% reduction in ad libitum feed intake. Lean growth rate (kg/d) was increased preferentially by ST in the faster-growing H × Y barrows, which showed a 2.8-fold greater maximum rate increase than the slower-growing Y × L barrows. In control barrows, 10% reductions in energy intake had no effect on lean gain and improved feed/lean gain about 10%. In somatotropintreated barrows, lean gain was reduced with each energy restriction in H × Y; energy intake had no effect on lean gain in Y × L barrows. Feed/lean gain was improved 22% in Y × L barrows at the lowest energy intake. Data indicate that somatotropin accentuates breed differences in lean gain and energy requirements. Pigs with low lean-growth potential will benefit from restricted feeding, whereas strategies to increase energy intake in pigs with high lean-growth potential may be desirable.

The growth rate of wool was measured at monthly intervals for a period of two years in four groups totalling forty Merino sheep, maintained under typical farm conditions in a Mediterranean climatic environment. Marked seasonal fluctuation in wool growth was found in all sheep. The highest level of clean wool production, 85 attained in the spring months, was nearly three times that of the lowest level, which occurred in the autumn. The rate of wool growth fluctuated independently of body weight. Wool growth fell steep4 while bob weight was maintained; wool growth subsequently rose sharply while body weight increased relatively slowly. The factors responsible for the observed fluctuation in the rate of wool growth are discussed and the conclusion reached that lack of useful energy and protein, in the summer and autumn grazing is probably the principal cause of the decline in rate of wool growth in these months.

The effect of high and lox- levels of feed intake during pregnancy in ewes, and from birth to 4 months of age in their lambs, on adult body weight and wool production has been studied. As compared with the corresponding high intake groups, lambs from the low intake ewes were 34% smaller at birth and 9% smaller at maturity. They also had c. 15% fewer wool follicles per sheep, and produced c. 8.5% less wool as adults. Low levels of feed intake between birth and 4 months resulted in a slower growth rate and a reduction (c. 10%) in mature body weight. The maturation of the follicle population was delayed by a low feed intake in this period but no permanent reduction in numbers was observed. The post-natal low intake group produced c. 12% less wool as adults, owing to a smaller (c. 10.5%) fibre weight. The major effect on wool growth potential of low levels of nutrient supply during pre-natal life was a restriction of body size and total number of follicles, while restriction of nutrient intake during early post-natal life reduced the capacity of the individual follicles to produce fibre.

Observations were made to determine whether differences between sheep in wool production under field grazing conditions reflected differences between individuals in feed intake. Sheep were selected for high, intermediate, and low levels of clean wool weight per unit body weight under field grazing conditions, and the feed intakes and wool production of these sheep were subsequently measured under pen conditions. On controlled feed intakes differences between sheep and between groups were less than those under field grazing conditions or under ad libitum pen feeding conditions. It was concluded that a, significant portion of the differences in wool production at grazing was referable to differences in feed intake. The group of sheep having high levels of wool production per unit body weight were found to have higher efficiency of conversion of feed to wool and also to have higher levels of feed intake under ad libitum feeding conditions. The rate of wool production of the high group was 22 per cent. greater than that of the low group under conditions of equal feed intake and 37 per cent. greater under conditions of ad libitum feed intake.

One hundred and thirty-seven samples of skin from six Indian breeds of sheep (Nilgiri, Bikaneri, Bellary, Black Kurumbai Adu, Mandya, and Nellore) were obtained from Madras and Andhra States in south India. The samples were collected, processed, and examined by the methods described by Carter and Clarke (1957a, 1957b). Representative values for (i) mean number of follicles per sq. millimetre of skin, (ii) ratio of secondary follicles to primary follicles, (iii) mean fibre diameter, and (iv) ratio of diameter of fibres in primary follicles to diameter of fibres in secondary follicles were: Nilgiri, (i) 16.0, (ii) 3.5, (iii) 26.0 µ, (iv) 1.2 ; Bikaneri, (i) 14.0, (ii) 2.0 , (iii) 35.0 µ, (iv) 1.7; Mandya, (i) 10.5, (ii) 1.8, (iii) 55.0 µ, (iv) 3.8 ; Bellary, (i) 6.6, (ii) 1.4, (iii) 56.0 µ, (iv) 3.1 ; Nellore, (i) 6.0 , (ii) 1.7, (iii) 60.0 µ, (iv) 5.3; Black Kurumbai Adu, (i) 7.8, (ii) 1.2, (iii) 48.0 µ, (iv) 2.0. On the basis of these examinations the Nilgiri is classified as a down-wool breed, the Bikaneri as a good carpet-wool breed, the Bellary, Mandya, and Black Kurumbai Adu as coarse carpet-wool breeds, and the Nellore as a hair sheep.

Variability of the lamb birthcoat has been studied in relation to adult fleece characteristics. Coarse birthcoats were associated with increased variability of fibre diameter and decreased crimp rate. The increased variability of fibre diameter resulted from a significant increase in the diameter of primary fibres and a small, but statistically non-significant, decrease in the diameter of secondary fibres. There was no relation between birthcoat grade and body weight, clean fleece weight, yield, staple length, follicle density, follicle ratio, mean fibre diameter, or skin folds. It is postulated that there is a gene system in the Merino the effect of which is to cause variation in the amount of wool produced by the different follicle types. Increased "dosage" of genes of the system endows primary follicles with increased productivity and secondary follicles with decreased productivity. This is expressed in the form of increased halo-hair abundance in the lamb and increased differences between the diameters of primary and secondary fibres in the adult.

The relationship between follicle number per unit area and wool production per unit area was examined in strong-wool (South Australian) and medium-wool (Peppin) Merino sheep. In four groups of strong-wool sheep (varying in number from 103 to 197 sheep) non-significant positive correlations were observed between follicle number per unit area and the amount of clean wool delineated by a 1 in. calliper. In two groups of strong-wool sheep (178 ewes and 169 rams) and one group of medium-wool sheep (184 ewes) the relationship between follicle number and unit area wool production was inferred from the association between number and fibre weight. There was a highly significant negative correlation (r = – 0.45 approx.) between number and fibre weight in each group. Further, a highly significant difference was observed between sire groups in mean fibre weight after adjustment for differences in follicle number. It was concluded that there was a small positive correlation between follicle number and wool production. This association was so small as to be of dubious biological significance. There were strong indications of a negative genetic correlation between follicle number and wool production, although this did not attain statistical significance.

The relationship of body weight to wool production was examined in a flock of Merino sheep of South Australian strain over a period of 7 years. In only one out of 10 groups examined was there a significant correlation between body weight and the amount of clean wool produced per unit area of midside skin. It is concluded that body weight and wool production per unit area of body surface are independent. In all groups there was a highly significant correlation between clean fleece weight and clean wool per unit area of body surface in the midside region. The regression of log fleece weight on log body weight was determined in 15 groups. In no case was the regression coefficient significantly different from 0.60. As the regression of log surface area on log body weight in sheep is of the order of 0.60, it is concluded that wool production is proportional to fleece-bearing surface. The mean regression coefficients of log fleece weight on log body weight, calculated within sire and year groups, were: rams, 0.52 ± 0.056; ewes, 0.61 ± 0.038; wethers, 0.30 ± 0.068. There were no significant differences between sires in the regression of log fleece weight on log body weight. There were, however, highly significant differences between sire groups in mean log fleece weight, after adjustment for differences in log body weight. Skin areas 3 by 3 cm were tattooed on the left midside of 24 lambs at 1 month of age. The wool produced on these areas, and the areas of the tattoos, were measured at 4-monthly intervals from 4 months of age until 28 months. The amount of wool produced m7as proportional to the area in each of the six periods. There was also a highly significant difference between periods and between sheep in the amount of wool produced after adjustment for differences in tattoo area.

The utilization of nitrogen was examined in sheep fed several diets; in some experiments the diet was supplemented with soluble casein given directly into the abomasum through a fistula. Casein supplements per abomasum were almost completely digested and absorbed. At the highest level of casein supplementation (55 g casein nitrogen per day) 95% of the casein was digested and absorbed. An increase in nitrogen intake resulted in an immediate increase in nitrogen balance, followed by a gradual return towards a stable level. There was also an immediate response of faecal and urinary nitrogen excretion to a change in nitrogen intake. Most of the adjustment in urinary nitrogen excretion occurred within 4 days, this period being followed by a gradual change towards a stable level of excretion during the next 6 weeks. Much higher levels of nitrogen retention were obtained from casein administered per abomasum than from similar levels of nitrogen given per os. Changes in wool production also occurred following changes in the nitrogen intake per 0s. The observed changes were variable, depending on the sheep and the feed change involved, and periods of up to 10 weeks were required before the rate of wool production became stable following a change in nutrition. Casein supplementation per abomasum resulted in a substantial increase in wool production and in a rapid increase in wool fibre diameter; most of the increase in fibre diameter occurred in the first week of supplementation. The efficiency of conversion of dietary nitrogen into wool nitrogen was much higher in experiments where a casein supplement was administered per abomasum than in experiments involving normal feeding; possible reasons for this difference are discussed.

Sheep on a sole diet of Leucaena glauca Benth. shed their fleece. The amino acid mimosine has been shown to be the depilatory agent. The depilatory effect of L. glauca was influenced by level and method of feeding. Small quantities of mimosine were excreted by sheep consuming L. glauca, but the major metabolite in the urine was identified as 3,4-dihydroxypyridine (DHP). It was established from the results of intravenous, intra-abomasal, and intraruminal administration of mimosine that sheep cannot detoxicate mimosine after absorption, but extensive degradation of mimosine to DHP takes place in the rumen. The absence of toxic symptoms in a sheep conditioned to L. glauca appeared to be due to increased detoxication in the rumen rather than to the development of an adaptive tolerance after absorption. The histological changes in the skin are described, and reasons for conflicting reports on the toxicity of L. glauca are discussed. A simple method for the isolation of mimosine from the seed of L. glauca is described in the Appendix.

Further observations on the inheritance of birthcoat grade in a flock of South Australian strain of Merino sheep are reported. These observations indicate that the inheritance is multifactorial and that the phenotypic variation is adequately accounted for by an additive genetic situation. The heritability of birthcoat grade was found to be 0.70 ± 0.035 from the regression of offspring on mid-parent and of the order of 0.72-0.78 from full-sib correlations. A difference, highly significant statistically, was observed between the birthcoat grade of ram and ewe lambs. Ewe lambs tended to be 0.35 grade coarser than ram lambs. Examination of published data (Rendel 1954) revealed that a similar difference also occurs between the sexes in the Welsh Mountain breed. A significant deficiency of female progeny was observed among the offspring of fine birthcoat ewes. There is no ready explanation of this loss but it almost certainly results from pre-natal death of a proportion of female embryos carried by fine ewes.

Observations are reported on factors affecting the ratio of secondary to primary follicles (SJP) in a flock of Merino sheep.It was found that all follicles were initiated prior to birth but that the number which finally came to maturity (production of fibre) was significantly affected by birth weight and growth from birth to 1 month. Growth at later ages appeared to be unimportant. There was a significant correlation (r = +0.29) between birth weight and log potential S/P at birth. This is interpreted to indicate that while pre-natal growth conditions affect the number of follicles initiated, other factors are also of considerable importance. It is concluded that the larger animals at birth also have a greater total number of primary follicles than smaller animals. It is further concluded that this difference in total primary follicles results primarily from differences in size a t the 90th day of pre-natal life rather than from differences in density a t that time.

Observations are reported on the development of the follicle population during post-natal life in three groups of sheep from a strain of Australian Merino. The primary follicle number is complete by birth, and changes in density thereafter merely reflect the normal skin expansion accompanying growth. This constancy with time of the primary follicle number validates the use of the ratio of secondary to primary follicles (S/P) as a measure of the development of the secondary follicles. The S/P ratio followed a sigmoid curve characterized by a small increase in the ratio during the first week, a large increase in the second, and a progressive decline in the rate of development of secondary follicles thereafter.

Observations were made on the effect of the presence of the ram when introduced to Merino ewes in the transition from the "non-breeding" to the "breeding" season in the Roseworthy environment. These observations showed that the primary effect was to stimulate ovulation without oestrus ("silent heat") in the majority of those ewes which had not already commenced cyclic breeding activity. This effect occurred within 6 days of joining the rams with the ewes. It is concluded that this mechanism explains the "lag and peak" incidence of oestrus previously observed under these conditions (Underwood, Shier, and Davenport 1944; Thompson and Schinckel 1952; Schinckel 1954).

The metabolic heat production of modern pigs has increased by an average of 16%, compared with sows of 30 years ago. Therefore, it is likely that temperature recommendations require updating to meet the needs of modern pigs. The objective of this study was to evaluate whether different reproductive stages of sows altered thermal preference and if current recommendations required updating. Twenty multiparous sows (3.4 ± 1.2 parity) in different reproductive stages (nonpregnant: n= 7; mid-gestation: 58.5 ± 5.68 d, n= 6; and late-gestation: 104.7 ± 2.8 d, n= 7) were tested. Thermal preference was individually tested, and sows could freely choose a temperature, using a thermal gradient between 10.4 and 30.5 °C. Sows were given 24 h to acclimate to the thermal apparatus. Before testing began, sows were given daily feed allotment and returned to the apparatus. Video from the 24-h test period was used to record sow behavior (time spent inactive), posture (upright and sternal and lateral lying), and location using instantaneous scan samples every 15 min. Data were analyzed using PROC MIXED procedure in SAS 9.4. A cubic regression model was used to calculate the sow’s most preferred temperature based on the location, or temperature, in which they spent the most time. The preference range was calculated using peak temperature preference ±SE for each sow. The reproductive stage altered where sows spent their time within the thermal gradient (P< 0.01). Late-gestation sows preferred cooler temperatures (14.0 °C) than mid-gestation (14.8 °C; P< 0.01) and nonpregnant sows (14.8 °C; P< 0.01). In summary, sow thermal preferences were within the lower half of the current recommended range (10 to 25 °C). This indicates that temperatures at the higher end of the recommended range could be uncomfortable to sows and that the thermal comfort zone of sows may be narrower than recommendations indicate.

Gestating sows may be more susceptible to increasing dry bulb temperatures (TDB) due to greater metabolic heat production and increased body mass, especially as gestation advances. However, there are few studies on the thermoregulatory and physiological responses of sows at differing gestation stages exposed to gradually increasing temperatures. The study objective was to determine the thermoregulatory and physiological responses of nonpregnant (n= 12; parity 3.27 ± 0.86), mid-gestation (59.7 ± 9.6 d pregnant, n= 12; parity 3.25 ± 0.83), and late-gestation (99.0 ± 4.8 d pregnant, n= 12; parity 3.33 ± 0.75) sows exposed to increasing TDB. Prior to the experiment (5.0 ± 0.7 d), jugular catheters were placed in all sows. During the experiment, the TDBwas increased incrementally by 2.45 ± 0.43 °C every 60 min from 19.84 ± 2.15 to 35.54 ± 0.43 °C over 400 min, and relative humidity was recorded at 40.49 ± 18.57%. Respiration rate (RR), heart rate (HR), skin temperature, and vaginal temperature were measured, and blood samples were obtained via the jugular catheter every 20 min. Data were analyzed using PROC MIXED in SAS 9.4. RR increased at a lower TDB(P< 0.01) in late-gestation sows compared with mid-gestation and nonpregnant sows, but no differences were detected between mid-gestation and nonpregnant sows. Overall, late-gestation sows had greater RR (P< 0.01; 23 ± 2 breaths per min [brpm]) compared with mid-gestation (16 ± 2 brpm) and nonpregnant (15 ± 2 brpm) sows. Late-gestation sows had an overall greater HR (P< 0.01; 84 ± 5 beats per min [bpm]) than mid-gestation (76 ± 5 bpm) and nonpregnant (69 ± 5 bpm) sows. Late-gestation sows had overall reduced bicarbonate and total carbon dioxide levels (P= 0.02; 23.89 ± 1.97 and 25.41 ± 2.07 mmol/L, respectively) compared with mid-gestation (27.03 ± 1.97 and 28.58 ± 2.07 mmol/L, respectively) and nonpregnant (26.08 ± 1.97 and 27.58 ± 2.07 mmol/L, respectively) sows. Moreover, late-gestation sows had overall greater nitric oxide levels (P< 0.01; 248.82 ± 34.54 µM) compared with mid-gestation (110.47 ± 34.54 µM) and nonpregnant (41.55 ± 34.54 µM) sows. In summary, late-gestation sows appear to be more sensitive to increasing TDBas indicated by thermoregulatory and physiological responses when compared with mid-gestation or nonpregnant sows. The results from this study provide valuable information regarding thermoregulatory thresholds of sows at differing gestation stages.

Dacitic tuff breccia (DTB) and poultry by-products (PBP) were added to nursery pig diets to evaluate their effects on growth performance in a 35 d experiment. A randomized complete block design based on BW and sex was used. Newly weaned pigs (N=564, 20.1 d of age, 6.18±0.006 kg initial BW) allotted to four diets (15 replicates/treatment; 9 or 10 pigs/pen): 1) Negative control (NC; no DTB or PBP), 2) NC+DTB (0.5% inclusion), 3) NC+PBP (4% chicken by-product meal + 2% feather meal – replacing fishmeal, corn, and synthetic amino acids in the NC), 4) NC+DTB+PBP. Phase 1–3 were each 7-d and Phase 4 was from d21-35. During week one there were no differences (P >0.10) among treatments. In week 2, pigs fed DTB tended to increase ADG (323 vs. 303 g/d; P=0.068) and ADFI (376 vs. 356 g/d; P=0.055) compared to pigs not fed DTB and pigs fed PBP tended to have increased ADG (P=0.093). In week 3 pigs fed PBP had reduced ADG (460 vs 483 g/d; P=0.011) and G:F (0.689 vs. 0.723; P< 0.001), and there tended to be an interaction for G:F (P=0.083) with DTB improving G:F when fed in combination with PBP but reducing G:F in the control diet. In week 4, feeding PBP decreased ADG (384 vs 415 g/d; P< 0.01) and ADFI (629 vs 666 g/d; P< 0.01) compared to pigs fed no PBP. There were no differences among treatments during week 5. For Phase 4 (d21-35) pigs fed PBP had decreased ADG (479 vs 497 g/d; P=0.041) and tended to have reduced ADFI (P=0.092) compared to pigs fed no PBP. Overall (d 0–35), there were no significant differences among treatments. In conclusion, DTB improved nursery pig growth performance early, however, pigs fed PBP had decreased ADG and feed efficiency late in the nursery period.

Lactating sows (N=140, York x Landrace) were used to evaluate the effects of a liquid prototype (LIQP) and dry (XPC®; Diamond V) Saccharomyces cerevisiae feed additives on sow and litter performance. Sows were fed a common gestation diet (0.55% SID-Lysine) until d112 of pregnancy and then allotted to lactation treatments: 1) Control diet (CON; 1.00% SID-Lysine), 2) CON +15 mL of LIQP from d112 to weaning (LIQ), 3) CON +0.20% of XPC from d112 to weaning (DRY), and 4) DRY +15 mL of LIQP from d112 to d7 post-farrowing (D+L). The LIQP was given once daily using an oral dose gun and XPC was included in the feed. Immunoglobulin concentrations were estimated on colostrum samples using Brix refractometer and piglet d 1 serum immunocrit ratio and plasma IgA and IgG. Daily sow water intake and daily feed intake (DFI) from d112 of gestation to d7 post-farrowing and weekly feed intake (ADFI) were recorded. There were no treatment effects on sow BW, backfat, or loin depth (P >0.05) although sows from LIQ group had numerically smaller BW reductions compared to CON sows (4.9% vs 7.2%, P=0.19). LIQ sows had greater DFI and CON lower DFI during week 1 of lactation (P=0.04) as well as ADFI for weeks 2, 3, and overall lactation period (P< 0.01) with DRY and D+L sows being intermediate. Water intake, immunoglobulins, and litter performance did not differ among treatments (P >0.05) although pigs from LIQ sows, compared to CON, had numerically increased weaning (6.14 vs 5.82kg, P >0.05) and litter weights (63.2 vs 60.1kg, P >0.05). LIQ sows had 0.7 d reduced wean-to-estrus interval (P< 0.001) and tended to have greater conception rates (P=0.07). In conclusion, LIQ supplementation of lactating sows improves feed intake, allowing sows to keep body reserves, and have better subsequent rebreeding performance.

A developmental Bacillus based direct-fed microbial (DFM) was added to nursery pig diets to evaluate the effect on growth and health in two 35-d randomized complete block design experiments blocked on initial BW and sex. Experiment 1 used 315 weaned pigs (20.1 d of age; 6.11 kg initial BW) allotted to one of three diets: 1) Negative Control (NC; no antibiotics but with pharmacological Zn or Cu), 2) NC+DFM 0.55x109CFU, 3) NC+DFM 1.1x109CFU. Experiment 2 used 376 weaned pigs (17.8 d of age; 5.99 kg initial BW) allotted to one of four diets, the same 3 diets from Experiment 1 plus a lower inclusion rate: 4) NC+DFM 0.275x109CFU. Both studies had 15 replicates/treatment, 6–7 pigs/pen. Pigs were budget fed phase 1–3 diets (1.13 kg/pig; 2.72 kg/pig; and 6.35 kg/pig, respectively) and ad libitum fed Phase 4 diet to d35. For Experiment 1, during week 1 pigs fed the DFM tended to linearly decrease ADFI (P = 0.086) and linearly increase G:F (P = 0.085). During day 21–35 of Experiment 1 pigs fed DFM linearly increased ADG (P = 0.035) and quadratically increased ADFI (P = 0.027). Overall for experiment 1, ADG (P = 0.114) and ADFI (P = 0.104) tended to quadratically increase and G:F linearly increased (P = 0.012) with increasing concentrations of DFM. Experiment 2; during week 1 and 3 ADFI (P = 0.084, P = 0.050, respectively) quadratically increased and G:F (P = 0.081; P = 0.022, respectively) quadratically decreased as DFM increased in the diet. During d21–35 of experiment 2, ADG (P = 0.064) quadratically increased and G:F (P = 0.012) quadratically decreased as DFM increased. Overall for Experiment 2 ADFI numerically increased (4.3%) with no increase in ADG, resulting in a quadratic decrease in G:F (P = 0.010) as the DFM increased in the diet. Summarizing these two studies, the DFM product had its greatest effect increasing ADFI while inconsistently impacting gain and efficiency.

Progeny from sows fed diets containing a Bacillus licheniformis direct-fed microbial (DFM), an organic acid blend of medium and short chain fatty acids (OA), DFM+OA, or a control (CON) diet from d80 of gestation until weaning were used to determine if feeding CON, DFM, OA, or DFM+OA to the dam and/or progeny post-weaning improved nursery growth performance. Weaned pigs from 47 dams (n = 384, Initial BW=6.15 kg) were blocked by initial BW and sex and allotted (6 pigs/pen, 8 pens/treatment) to one of 8 nursery treatments. Pigs from CON sows were fed a negative (NC; no antibiotics, pharmacological Zn or Cu) or positive [PC; Neo-Terramycin phases 1 and 2 (827 and 551 ppm) and Carbadox phase 3 (55 ppm)] control diet. Pigs from sows fed DFM, OA, or DFM+OA were fed the NC diet or a diet representative of their dam. Diets with DFM contained 1.6x109CFU/kg DFM and diets with OA contained 0.5, 0.4, and 0.3% OA in phases 1–3, respectively. Weaning weight was used as a covariate for nursery performance. For all phases and overall, PC fed pigs had greater ADG, ADFI, and G:F (P < 0.05). Feeding DFM or OA in sow diets improved (interaction; P< 0.042) nursery pig G:F, but DFM+OA offspring had no improvement for d7–14, 0–14, and 0–21 G:F. Feeding DFM or OA to sows and their progeny decreased ADFI (interaction; P < 0.042) but improved G:F (interaction; P < 0.028) for d7–14 and 0–14 with DFM+OA having no improvement above CON. For d14–21 and 0–21, feeding DFM or OA to sows and their progeny decreased ADFI whereas DFM+OA increased ADFI above CON (interaction; P < 0.019). In conclusion, feeding DFM or OA to sows or their offspring may improve nursery feed efficiency and feeding DFM+OA diet to sows and their progeny may increase ADFI late in the nursery period.

This study was designed to evaluate the effects of electronically controlled cooling pads on measures of physiological responses in HS gilts. The study utilized 12 gilts randomly assigned into one of three treatment groups [Control(CN), flush 2.0 L cool water over 30 s every 4 min(F4), or flush 2.0 L over 30 s every 8 min(F8)] in a Latin Square design and replicated 12 times(2 repetitions/d over 6 d). Gilts were housed in farrowing crates and fed 1.2 kg at 0700 and 1300 h daily. On d 1 to 3(6 repetitions) the room was gradually heated from 18ºC to 32ºC, while on d 4 to 6 the room was gradually heated from 18ºC to 35ºC starting at 0730 or 1330 h. Once the temperature was achieved, cooling pads were turned on and the temperature was maintained for 2.5 h. Two baseline measurements were taken of respiration rates(RR), skin temperature through thermal imaging(IRTemp), and vaginal temperature(VTemp) before room heating began and then recorded every 20 minutes after pads were turned on. Measurements at the end of HS(PostH) and the change in values during the HS period(DIFF) were evaluated using PROC mixed of SAS. Gilts in F4 and F8 had lower RR than CN for PostH for both 32ºC and 35ºC (P< .05). DIFF in RR was less in F4 and F8 than in CN[(32ºC, P=.097) and (35ºC, P=.005)]. There was a tendency for DIFF in Vtemp at 32ºC between treatments (P=.064) but had no effect by treatment for PostH (P=.534). There was no effect in PostH and DIFF for IRTemp between treatments for 32ºC and 35ºC. PostH and DIFF for VTemp were significant at 35ºC (P=.009 and P=.001). PostH for RR was different at 35 ºC and 32 ºC (P=.0074; P=.0472) with F4 and F8 lesser and CN. In conclusion, cooling pads, regardless of flush rate, had positive impacts on physiological indicators of HS.

This study was designed to evaluate the effects of electronically-controlled floor cooling pads on thermoregulatory and reproductive parameters in boars during heat stress (HS). Boars (n = 24) were randomly assigned to crates with non-functional pads (CON) or pads that were flushed in either 8-min intervals or when the pad reached 28.5°C (FLUSH). For 3 d, boars were subjected to cyclical HS (28 to 35°C; >65% relative humidity). Boars were fed 2.4 kg/d and daily feed intake was recorded. Respiration rate (RR), rectal temperature (Rtemp) and skin temperature were recorded every 2 h during HS (via IR camera), testicular temperature was recorded twice daily. Semen was collected d7 and d14 before HS, the day following HS and weekly for 6 weeks and evaluated for volume, sperm concentration, motility, progressive motility, morphological abnormalities, and viability. After 2 h of HS, FLUSH boars had reduced RR (P < 0.001) and RTemp (P < 0.001) when compared to control boars, and this difference was maintained throughout HS. Skin and testicular temperature were reduced in FLUSH vs. CON boars after 6 h of HS (P < 0.05). Semen volume was greater in FLUSH vs CON boars (P = 0.01) resulting in a tendency for an increase in total sperm per ejaculate (P = 0.075). From weeks 2 to 5 post-HS, FLUSH boars had increased motility (P = 0.006) and progressive motility (P = 0.001), with corresponding increases in sperm kinematic motion parameters when compared to CON boars. The number of morphologically normal sperm cells were increased (P = 0.006) in FLUSH vs CON boars due to reduced distal droplets (P = 0.033) and proximal droplets (P < 0.001). Abnormal acrosomes were reduced (P < 0.001) in FLUSH vs CON boars at week 3 post-HS. In summary, electronically controlled cooling pads effectively reduced negative thermoregulatory indicators of HS and minimized or removed the negative impacts of HS on semen quality in boars.

The effectiveness of sow cooling pads during lactation was evaluated under mild and moderate heat stress conditions to reduce indicators of heat stress. The moderate heat stress rooms (n =2) were targeted to achieve 32ºC from 0800-1600 h and 27ºC for the rest of the 24-hour day. The mild heat stress rooms (n=2) were targeted to achieve 27ºC and 22ºC for the same periods, respectively. Yorkshire-Landrace sows were blocked by parity and BW, and assigned to two farrowing rooms which differed only in environmental temperature. Each sow was provided a cooling pad made with aluminum plate on top, a high-density polyethylene base, and eight copper water pipes. Sows received either a constant cool water flow of 0.00 (CONTROL, n = 9), 0.25 (LOW, n = 12), or 0.50 (HIGH, n = 10) L/min. Water inlet and outlet temperatures and flow rates were recorded to estimate heat removal. Respiration rates (RR) were measured for 2 -30 second intervals. Rectal temperatures (RT), skin temperatures 15 cm behind the ear (ST) and RR’s were recorded every day (0700 and 1500 h) from the second day in the farrowing room to weaning. The sow RR, ST, RT and estimated heat removal were affected (P< 0.036) by pad treatment (PT), time of day, room temperature (RTEMP), day of lactation, and all two variable interactions. The RR increased (P< 0.001) as heat stress increased. The difference in heat removal between the HIGH and LOW flow rates was 16 watts (132.1 versus 116.1) in the mild heat stress rooms, but increased to 43.4 watts in the moderate heat stress rooms (181.4 versus 138.0, (P = 0.048 for RTEMP × PT). Sow cooling pads reduced measures of heat stress. The results indicate that the LOW flow rate is adequate from 22 to 27ºC (with 40 to 45 % relative humidity) but the HIGH flow rate is needed at temperatures above 27ºC.VariablePad TreatmentMild – 700 hModerate – 700 hMild – 1500 hModerate – 1500 hRRCON23564189LOW21242941HIGH18202427STCON35.437.337.237.3LOW34.436.536.636.5HIGH33.736.236.536.2RTCON38.839.039.239.6LOW38.838.839.139.0HIGH38.838.839.139.0

The objective was to compare selection indexes based on the production costs and economic values from the United States and China. Indexes with dollar values including terminal sire (TSI), maternal line (MLI) and sow productivity (SPI) indexes were calculated based on the production costs and market prices for the U.S. and China. Estimated breeding values for: days to 113.5 kg, backfat depth, loin muscle area, number born alive, number weaned, litter weight adjusted to 21 days, days from weaning to estrus, and litter birth weight were provided by a Chinese pig breeding company to evaluate alternative STAGES indexes. The Duroc data included 39 sires, 5,079 boars and 5,368 gilts. The Landrace data included 199 dams, 83 sires, 2,749 boars and 2,750 gilts. The Yorkshire data included 1,368 dams, 139 sires, 18,481 boars and 17,962 gilts. The means, standard deviations, and correlations for the EBV’s and indexes were calculated. The Chinese TSI values were more highly correlated (R = 0.97 to 0.99, P<0.001) with the U.S. indexes than the MLI values (R=0.92 to 0.97, P<0.001). Overall, the Chinese indexes had greater SD’s (TSI, 58 to 87% greater; SPI, 22 to 26% greater; MLI, 43 to 76% greater). The TSI’s were all highly correlated (R > 0.98, P<0.001) with feed efficiency. The Chinese MLI values had greater correlations with TSI and lesser correlation with SPI than the U.S. indexes. The Chinese MLI placed greater emphasis and subsequently greater predicted rates of genetic progress for the post weaning traits and lesser emphasis on sow productivity traits than current U.S. MLI. Alternative Chinese indexes were evaluated with or without market value based on carcass lean percentage. In the U.S., the carcass value was determined based on the curvilinear economic relationship between carcass value and lean percentage. The Chinese TSI including carcass value relative to carcass lean percentage placed greater emphasis on carcass leanness traits (backfat depth and loin muscle area) with less emphasis on growth rate than the Chinese TSI without carcass premium for carcass lean percentage. The Chinese MLI including carcass value relative to carcass lean percentage also placed greater emphasis on the carcass leanness traits with less emphasis on growth rate and reproductive traits (number born alive, number weaned and litter weight adjusted to 21 days) than the Chinese MLI with no carcass premium for carcass lean percentage. The greater Chinese feed cost results in greater emphasis for feed efficiency.

States that in order to be competitive in the hog and pork world wide market the United States (U.S.) must lower prices in relation to other meats. Details on the growth which will be provided under the Expanded foreign markets under the General Agreement on Tariff and Trade and the North American Free Trade Agreement; Indication that reliance on foreign trade will add instability t the U.S. markets.

Focuses on the structural transformation involving changes in product characteristics relating to the United States hog and pork sector. Reference to the sector shifting from the traditional Midwest to other parts of the nation and world; Information on the performance of domestic pork production; Reference to the growth of annual pork production; Details on the restructuring..

The first objective was to evaluate the effect of dietary betaine supplementation on sow lactation and postweaning performance during summer conditions. Sows were supplemented with either 0.00 or 0.21% dietary betaine (193 and 175 sows, respectively). Betaine-supplemented sows had 3.90% greater ADFI during lactation than control sows (P= 0.005). Treatment × parity interactions were significant for ADFI and BW loss (P< 0.008). Parity 2 betaine-supplemented sows had 0.72 kg/d greater ADFI and 6.70 kg less BW loss than parity 2 control sows (P< 0.022). Betaine-supplemented sows had greater ADFI in the 6- to 11-d, 12- to 16-d, and 17- to 21-d periods (P< 0.019). Wean-to-estrus intervals (WEI) were 0.31 d shorter (P= 0.004) and had different distribution (P= 0.029) for betaine-supplemented sows than for control sows. Greater percentages, 3.2 and 12.1% of betaine-supplemented sows, returned to estrus on d 3 and 4, respectively, than control sows. In another lactation trial, sows supplemented with 0.21% dietary betaine had 0.51 mm greater follicle diameter (P= 0.043) and 0.23°C lower rectal temperature (P= 0.048) than control sows. The second objective was to develop a cooling pad that efficiently removes excess of heat from lactating sows. Cooling pads were built with an aluminum plate surface, high-density polyethylene base, and copper pipes. Respiration rates and rectal, vaginal, and skin temperatures for 8 replicates of 10 sows were evaluated after 100 min of cooling with different constant cool water flows of 0.00 (4 sows), 0.25 (2 sows), 0.55 (2 sows), or 0.85 L/min (2 sows). The cooling was initiated 1 h after the room reached 35°C. Mean room temperature and relative humidity during the trial were 35.1 ± 0.4°C and 68.4 ± 3.2%, respectively. The 0.55 and 0.85 L/min treatments reduced respiration rates and rectal, vaginal, and skin temperatures after 80 min of cooling (P< 0.001). Respiration rates decreased within 20 to 40 min for sows on the 0.85 L/min treatment (P< 0.001). Overall, heat removal during the trial was 193, 321, and 365 W for the 0.25, 0.55, and 0.85 L/min treatments, respectively (P< 0.001). Betaine supplementation can alleviate some of the heat stress effects in lactating sows. Cooling pads have a greater potential than betaine to reduce heat stress in lactating sows. Initial data indicate that pulsing of cooled water results in more efficient heat transfer per liter of water.

The objective was to estimate the impact that the accuracy in which pigs are sorted for marketing has on the optimal market carcass weight (CW) and economic returns. Two types of errors were evaluated in a stochastic model, BW estimation error (BWEE) and percentage of pigs not visually evaluated (PNVE). Pigs are not evaluated when the targeted number of pigs are identified and sorting stops with heavier pigs than those sorted not being evaluated. Four levels of BWEE with SD's of 0, 4, 6, and 8% of BW and 4 levels of PNVE (0, 8, 16, and 24%) were simulated. Initially, pigs were marketed in 3 marketing cuts (MCUT), 25% at 169, 25% at 179, and the remaining 50% at 193 d of age. The timing of marketing was shifted in 7 d intervals with mean marketing ages of 155.5 to 211.5 d with mean CW's of 75.7 to 108.7 kg. Sort loss was calculated using a market system for a U.S. pork processor (IPC, Delphi, IN). Mean for sort loss ($/pig) values for the pigs in the barn were fitted to a polynomial function of mean CW for each combination of BWEE and PNVE. The increase in mean sort loss for each unit increase in CW above 93 kg increased as BWEE and PNVE increased. Pork production costs were estimated using an industry spreadsheet. A base price of $1.433/kg of CW was used to produce a small profit per pig. Lean premium (LPREM, $/100 kg CW) for gilts was estimated as LPREM = 0.4665 – 0.00198 CW, kg (R2= 0.99) and for barrows was LPREM = 0.4176 – 0.00216 CW, kg (R2= 0.99). The optimal CW's to maximize profit/pig and daily returns above daily costs were estimated for each combination of BWEE and PNVE. With accurate sorting, (BWEE = 0, PNVE = 0%) the optimal mean age for the 3 MCUT strategy was 190.5 d (176, 186, and 200 d MCUTs) at a mean CW of 97.0 kg and profit of $3.35/pig. With less accurate sorting (BWEE = 8%, PNVE = 24%), the optimal mean age decreased to 184.5 d with mean CW of 93.4 and profit of $2.00/pig. The optimal market ages and CW's decreased as the accuracy of sorting pigs decreased. The impact of inaccurate sorting of market hogs on the optimal market BW is impacted by several factors (marketing grid, feed costs, market prices, etc.).

The objective was to evaluate the effects of floor cooling on lactating sows under severe summer heat stress. Twelve multiparous sows were provided with a cooling pad built with an aluminum plate surface, high-density polyethylene base, and copper pipes. Treatments were randomly allotted to sows to receive a constant cool water flow of 0.00 (CONTROL; n= 5), 0.25 (LOW; n= 3), 0.55 (MEDIUM; n= 2), or 0.85 L/min (HIGH; n= 2) for 90 min. The cooling was initiated 1 h after the room reached 35°C. Respiration rates (RR), rectal temperature (RT), and skin temperature (ST; 15 cm posterior to the ear) were recorded before the trial, prior to cooling, and after 90 min of cooling. Water flow rates and inlet and outlet water temperatures were recorded 6 times (every 15 min) to calculate the heat removal (watts) after cooling initiation. In all 3 replications, treatments were randomly switched between sows. Data were analyzed using the MIXED procedure in SAS (SAS Inst. Inc., Cary, NC). Respiration rate, RT, ST, and heat removal were analyzed using repeated measures with compound symmetry covariance structure with sow as a repeated random effect. For RR, RT, and ST measurements, the model included treatment and phase (before trial, prior to cooling, and at the end of the trial) and their interactions as fixed effects and replication as a random block. For the cooling phase, heat removal model included treatment and cooling time and their interactions as fixed effects and replication as a random block. The mean room temperature and relative humidity during the trial were 35.3 ± 0.7°C and 57.8 ± 3.1%, respectively. The treatments impacted RR, RT, and ST after 90 min of cooling. At the end, mean RR were 132, 89, 71, and 31 breaths/min for the CONTROL, LOW, MEDIUM, and HIGH treatments, respectively (P< 0.001). The mean RT and ST were 39.9 and 39.8°C, respectively, for the CONTROL; 39.5 and 39.1°C, respectively, for the LOW; 39.2 and 38.8°C, respectively, for the MEDIUM; and 39.1 and 39.2°C, respectively, for the HIGH treatments (P< 0.001 and P= 0.079, respectively). Overall heat removal during the trial was 196.2, 278.3, and 320.7 W for the LOW, MEDIUM, and HIGH treatments, respectively (P< 0.001). Cooling pads with MEDIUM and HIGH water flow rates reduced RR and RT in lactating sows.

A study was conducted to investigate the whole body amino acid (AA) composition profile of barrows and gilts of 2 genetic lines with high and low lean growth rate (high-lean= 375 g of fat-free lean/d; low lean= 280 g of fat-free lean/d) from 20 to 125 kg of BW. A total of 120 growing pigs were slaughtered with a 2 (genetic line) × 2 (sex) × 5 (BW group) factorial arrangement of treatments. At 20 kg of BW and at 25 (or 30) kg BW intervals, 6 pigs of each genetic line and sex were slaughtered and body components were ground to determine the composition of water, crude protein (CP), fat, ash, and AA. Whole body AA composition was expressed as g/kg BW and g/100g CP. PROC MIXED procedure of SAS (9.4) and contrasts were constructed to analyze the data. Total body AA content for barrows and gilts were 119 vs. 119, 124 vs. 126, 116 vs. 121, 116 vs. 124, and 121 vs. 124 g/kg BW, for BW at 20, 45, 75, 100, and 125 kg, respectively. Total AA content for high- and low-lean genotype were 123 vs. 116, 131 vs. 120, 122 vs. 115, 127 vs. 113, and 129 vs. 115 g/kg BW, for the 5 BW stages. Between the barrows and gilts, the whole body composition (g/kg BW) of total essential AA and total AA was similar in all BW group except for 100 kg (P< 0.05). From 45 to 125 kg of BW, high-lean genotype showed greater AA content (g/kg BW) of all the essential AA and total AA in all the BW groups. The AA content (g/kg BW) changed in cubic pattern for most AA and total AA along with the increased BW (P< 0.05). The AA profile in whole body CP (g/100g CP) demonstrated a similar AA profile in whole body AA composition between barrows and gilts across BW groups. Genotype affected the AA profile (g/100g CP) for all the essential AA (P< 0.01) except for arginine. Compared with low-lean pigs, high-lean genotype exhibited greater concentrations of isoleucine, lysine, and methionine in CP in all the BW groups greater than 45 kg (P< 0.05). The results indicated that genotype and gender can affect the whole body composition and profile of AA. The genotype of high- and low-lean can impact the AA profile in whole body protein.

The objective was to evaluate relationships between changes in physiological measurements and estimated heat removal (HR) of lactating sows on cooling pads. Moderate heat stress rooms were targeted to achieve 32ºC from 0800-1600 h and 27ºC for the rest of the 24-hour day. Mild heat stress rooms were targeted to achieve 27ºC and 22ºC for the same periods, respectively. Each sow was provided a cooling pad with either a constant cool water flow of 0.00 (CONTROL, n = 9), 0.25 (LOW, n = 12), or 0.50 (HIGH, n = 10) L/min. Water inlet and outlet temperatures and flow rates were recorded to estimate HR. For the overall trial, respiration rates (RR), rectal temperature (RT), and skin temperature (ST) were recorded every day (0700 and 1500 h) from the second day in the farrowing room to weaning at 17 to 20 d. Regression analyses were used to evaluate changes in RT and RR relative to estimated HR. The difference in RT and RR for sows on the LOW and HIGH pads relative to the CONTROL sows was calculated for each AM and PM measurement. The change in RR per watt of HR were similar for the LOW and HIGH pads (b = -0.626 and -0.586) with lower R2values for LOW than HIGH pads (0.424 versus 0.698). The change in RT per watt of HR were greater (P< 0.05) for the LOW than HIGH pads (b = -0.0091 versus -0.0066) and R2values were less for LOW than HIGH pads (0.188 versus 0.399). An intensive 2-d study was performed on sows in the moderate heat stress room on the CONTROL (n = 3) and HIGH (n = 3) treatments (14.2 ± 1.8 d of lactation). Respiration rate, and RT were recorded at 0600, 0700, 0730, 0800, 0830, 1100, 1400, 1500, 1530, 1600, 1630, and 1900 h. The cooling pad treatment affected RR (52 and 30 breaths/min, CONTROL versus HIGH, P < 0.05). The RR of CONTROL sows increased as the room temperature increased (P< 0.05) after 0830 h and remained higher until 1600 h. The RR of HIGH sows did not change between 0830 and 1700 h. The HR rates were affected (P< 0.003) by measurement time. The greatest HR (220-230 watts) were from 1530-1630 h. The effect of cooling pads to reduce RR and RT increased as the room temperature and HR increased.

The objectives of this research were to quantify and model daily feed intakes (DFI) of lactation diets to 28 d of lactation in modern sows. A total of 4512 DFI records were collected for 156 Hypor sows from February 2015 to March 2016. The mean lactation length was 27.9 ± 2.0 d, overall mean = 7.31 kg/d). Data included 9 parity 1, 33 parity 2, and 114 parity 3+ sows. Data were collected using a computerized feeding system (Gestal Solo, JYGA Technologies, Quebec, Canada). The feeding system was used to set an upper limit to DFI for the first 7 d of lactation. Overall, the least-squares means of a model including the random effect of sow indicated that DFI's continued to slowly increase to 28 d of lactation. The DFI data were fitted to Generalized Michaelis-Menten (GMM) and polynomial functions of day of lactation (t). The GMM function [DFIi,t(kg/d) = DFI0+ (DFIA– DFI0)(t/K)C/[1 + (t/K)C]] was fitted with 2 random effects for DFI (dfiAi) and intercept (dfi0i) using the NLMIXED procedure in SAS®. The polynomial function DFIi,t(kg/d) = [Bo+ B1t + B2t2+B3t3+ B4t4] was fitted with three random effects for Bo, B1, and B2using the MIXED procedure in SAS®. Fixed effects models of the two functions had similar Akaike Information Criteria (AIC) values and predicted DFI. The polynomial function with 3 random effects provided a better fit to the data based on R2(0.81 versus 0.79), AIC (14,709 versus 15,158), and RSD (1.204 versus 1.321) values than the GMM function with two random effects. The random effect for B2allowed for the fitting of the function to lactation records that had decreased DFI after 15 d of lactation. The random effects were used to sort the lactation records into three groups based on the derivative of the polynomial function at 21 d of lactation. Lactation records of the three groups had similar DFI the first 2 wk of lactation (P> 0.40). The three groups of sows had substantially different DFI after 21 d of lactation (10.7, 9.1 and 6.9 kg/d, P< 0.001). The differences in actual and predicted DFI between the three groups increased with each day of lactation to Day 28 (P< 0.001). Mixed model polynomial functions can be used to identify sows with different patterns of DFI after 15 d of lactation.

The BW growth curves for 25, 4000-head finishing barns were simulated to 1) evaluate the impact of sorting errors on sort loss at different mean carcass weights (CW) and 2) demonstrate that the magnitude of sort loss due to inaccurate sorting is affected by the pigs' mean CW. Two types of errors were evaluated, BW estimation error (BWEE) and percentage of pigs not visually evaluated (PNVE). Pigs are not evaluated when the targeted number of pigs are identified and sorting stops with heavier pigs than those sorted not being evaluated. Four levels of BWEE with SD's of 0, 4, 6, and 8% of BW and 4 levels of PNVE (0, 8, 16, and 24%) were simulated. Sort loss was calculated using a market value system for a U.S. pork processor (IPC, Delphi, IN). Pigs were initially marketed in 3 marketing cuts, 25% at 169, 25% at 179, and the remaining 50% at 193 d of age. Marketing ages for the pigs were shifted in weekly intervals with mean ages of 155.5, 162.5, 169.5, 176.5, 183.5, 190.5, 197.5, 204.5, and 211.5 d of age. Two variables, number of pigs with sort loss and mean sort loss per pig in the barn, were fitted to a model including the fixed effects of level of marketing age (AGE), BWEE, PNVE, their interactions and random effect of replicate barn using the MIXED procedure of SAS®. The main effects of AGE, BWEE, and PNVE and AGE × PNVE, AGE × BWEE, and AGE × BWEE × PNVE interactions impacted both variables (P< 0.001). The effects of BWEE and interaction of BWEE × PNVE impacted (P< 0.001) both variables at all ages. The difference in sort loss/pig produced by the least accurate sorting (BWEE = 8% and PNVE = 24%) increased as the mean CW increased from $1.00 at 93 kg to $4.53 at 103 kg. Sort loss/pig increased more rapidly with increased CW at higher levels of BWEE and PNVE. The effect of inaccurate sorting to increase sort loss is minimized when the mean CW is close to the middle of the pork processor's acceptable CW range and increases as CW increases to those approaching the upper acceptable CW range and is dependent on the marketing grid.

The objectives of this research were to develop a model of heat production for lactating sows to estimate differences due to genetics, parity, and day of lactation and to estimate the magnitude of daily sow to sow variation. The model was developed using NRC (2012). Sow body weight (BW), mean daily litter weight gain (Cabezón et al., 2016a), and daily feed intake (DFI) data (Cabezón et al., 2016b) from 317 sows of 2 genetic lines, C-22 (n= 164) and L-42 (n= 153), were used to predict the heat production (watts) for each day of lactation. The data were sorted in 4 parity groups, parity 1 (n= 80, P1), parity 2 (n= 57, P2), parities 3 to 5 (n= 142, P3–5), and parity 6 and greater sows (n= 38, P6+). The variance of the predicted mean daily heat production (PMHP, watts, d 1 to d 21 of lactation) was calculated using the partial regression coefficients and variances for sow BW, mean daily litter weight gain, and DFI. A two-sample ttest was performed to test for significant differences for PMHP between genetic lines and parities. Parity group differences were similar for the genetic lines (P> 0.05). No differences were observed for PMHP between genetic lines (P> 0.05). The PMHP were 459.2, 507.3, 541.3, and 554.7 W for P1, P2, P3–5, and P6+ sows, respectively. Parity 1 sows had less PMHP than all greater parity sows (P< 0.05). Parity 2 sows had less PMHP than P3–5 and P6+ sows (P< 0.05). No difference was found in the PMHP between P3–5 and P6+ sows (P> 0.05). The coefficients of variation were 18.4, 17.6, 17.1, and 15.5% for P1, P2, P3–5, and P6+ sows, respectively. Within a parity, variation in DFI accounted for approximately 95% of the variation in PMHP. The model was also applied to older data (Shurson et al., 1986; Noblet and Etienne, 1987) with lower sow productivity. The model estimated that the current sows produce approximately 24 to 39% more heat than past sows. Heat production increases with parity, and there is substantial variation for PMHP within sows of the same parity. Strategies to remove the excess heat production of lactating sows in high environmental temperatures should try to account for sources of variation in heat production.

This study was conducted to evaluate the underlying physiological changes that occur during heat stress and the effect of betaine supplementation in lactating sows. Twenty sows were housed in two rooms (each with 10 sows) to simulate heat stress (HS: 31°C from 8:00 to 16:00 and 26°C for the rest of the day) or thermoneutral (TN: 22°C during the entire trial) conditions. Treatments were randomly allotted to each sow to receive 0.00% or 0.22% of a betaine supplement in their diets. Sows were blocked by parity as they entered the farrowing rooms at Day 110–112 of gestation. Sows housed in the HS condition had ad libitum access to feed. Sows housed in the TN condition were pair fed with sows in the HS room. Data were analyzed as a 2 × 2 factorial arrangement of treatments, with 2 levels of room temperatures and 2 dietary betaine levels. Respiration rates and rectal and skin temperatures were recorded every day (7:30 and 15:30) from the first day in the farrowing room to weaning. Blood samples from sows were taken at different days during the trial (before move in, Day 7, 14, weaning and 3 d post-weaning). Follicle size was measured every 12 h with a real time ultrasound from weaning to ovulation. Treatment by room interaction was not significant for any variable (P> 0.11). Betaine supplemented sows had 0.23°C lower rectal temperature than control sows (P= 0.048). Respiration rates and rectal and skin temperatures were 35.6 breaths/min and 0.4 and 3.6°C greater under HS than TN conditions, respectively (P< 0.004). Homocysteine and cortisol serum concentrations did not differ between treatments (P> 0.44) or environments (P> 0.25). Betaine supplemented sows had 0.51 mm greater follicle diameter than control sows at the same times post-weaning (P= 0.043). The mean follicle diameter was 0.97 mm smaller under HS than TN conditions (P= 0.003). Regression analysis indicated that room temperature differences in follicular size were due to differences in the time of follicular growth initiation and not in the rate of growth. The follicle size at ovulation did not differ between housing conditions (P= 0.79), but the time from weaning to ovulation was 2.1 d greater in HS than TN sows (P= 0.005). Heat stress affects follicle size at the same hours post-weaning and delays the time of ovulation but does not affect follicle's size at ovulation.