Evaluation of increased fiber, decreased amino acids, or decreased electrolyte balance as dietary approaches to slow finishing pig growth rates

In swine production, pig movement restrictions or packing plant closures may create the need to slow growth rates of finishing pigs to ensure they remain at a marketable body weight when packing plant access is restored. Although dietary formulations can be successful at slowing pig growth, precision is needed regarding how to best formulate diets to achieve growth rate reductions. Thus, the objective was to evaluate three dietary experimental approaches aimed at slowing growth rates in finishing pigs. These approaches consisted of either increasing neutral detergent fiber (NDF), reducing essential amino acids or reducing the dietary electrolyte balance through the addition of acidogenic salts. Ninety four mixed-sex pigs (72.4 ± 11.2 kg BW) across two replicates were individually penned and assigned to 1 of 8 dietary treatments (n=11-12 pigs/treatment): 1) Control diet representative of a typical corn–soybean meal-based finisher diet (CON); 2) diet containing 15% NDF from soybean hulls (15% NDF), 3) diet containing 20% NDF from soybean hulls (20% NDF), 4) diet containing 25% NDF from soybean hulls (25% NDF), 5) diet formulated as per CON but with 50% of the soybean meal replaced with corn (89% Corn), 6) diet containing 97% corn and no soybean meal or synthetic amino acids (97% Corn), 7) diet containing 2% anhydrous calcium chloride (2% CaCl2), and 8) diet containing 4% anhydrous calcium chloride (4% CaCl2). Over 28 d, pig body weights and performance were recorded weekly. At d 28, all pigs were ultrasound scanned and switched to the CON diet to evaluate compensatory gain from d 28 to 35. Overall, increased NDF did not impact any growth performance parameter (P > 0.05). Amino acid restriction reduced ADG, ADFI, and G:F linearly (linear P < 0.001). Similarly, ADG, ADFI, and G:F were linearly reduced with increased CaCl2 inclusion (linear P < 0.001). Average daily gain differed during the compensatory gain period (P < 0.001), with 4% CaCl2 fed pigs having a 47% increase in ADG compared with CON fed pigs. Conversely, 15% and 25% NDF fed pigs had reduced ADG compared with CON fed pigs during the compensatory gain period. Gain efficiency differed from day 28 to 35 (P < 0.001), with 4% CaCl2 fed pigs having a 36% increase in G:F compared with CON fed pigs. Altogether, these data demonstrate that both amino acid restriction and CaCl2 inclusion are effective at slowing pig growth, albeit at greater inclusion rates.

205 Dietary Strategies to Limit Average Daily Gain of Late Finishing Pigs

A total of 2,164 pigs [DNA610 x DNA241; initially 100.7 ± 2.14 kg body weight (BW)] were used in a 54.1 ± 3.85-day study to determine dietary strategies to limit average daily gain (ADG) in late finishing pigs raised in a commercial environment. Mixed-sex pens (20.0 ± 0.85 pigs/pen) balanced by initial BW and gender ratio were randomly assigned to 1 of 4 dietary treatments fed ad libitum with 27 replications each: (1) Nutritionally replete corn soybean-meal control (CTRL), (2) Treatment 1 with 21% reduced lysine and other amino acids (AAR), (3) Corn/vitamin/mineral diet (CVM), and (4) Treatment 3 fed for 21 days then switched to CTRL. Data were analyzed as a randomized complete block design using a linear mixed model. Relative to CTRL, feeding AAR or CVM for 21 days reduced ADG (P < 0.001), average daily feed intake (ADFI; P = 0.005), and gain-to-feed (G:F, P < 0.001). Over 55-days, AAR and CVM diets reduced (P < 0.001) cumulative ADG, ADFI, G:F, and final BW compared to CTRL. Transitioning to CTRL diet from CVM diet after 21-days increased ADG (P < 0.001) and improved G:F (P < 0.001) from day 21 to marketing compared to 55-day CTRL, AAR, and CVM; nevertheless, the compensatory CTRL period was insufficient for the 21-day CVM fed pigs to fully compensate resulting in reduced cumulative BW, ADG (P < 0.001) and poorer G:F (P < 0.001) than the 55-day CTRL. All holding strategies decreased (P < 0.001) carcass yield, hot carcass weight (HCW), and loin depth compared to CTRL. Utilizing a CVM diet for 21 or 55 days increased (P < 0.001) backfat compared to CTRL or AAR. In summary, utilizing lysine deficient or corn/vitamin/mineral diets can limit ADG along with poorer G:F. Transitioning to a non-holding diet after feeding a corn/vitamin/mineral diet for 21-days resulted in compensatory gain, but reductions in growth performance and carcass traits remained evident.

Performance and serum parameters of calves (Bos taurus) subject to milk restriction associated with supplementation with 2-hydroxy-4-methylthiobutanoic acid

Our aim, with this study was to evaluate the consumption, performance, quantitative characteristics of carcasses, biochemical profile, plasma levels of ghrelin and leptin, expression of the receptor for ghrelin (GHS-R1a) in the hypothalamus and duodenum, and the number of goblet cells in the duodenum of calves subjected to milk volume restriction and supplemented with 2-hydroxy-4-(methylthio)butanoate acid (HMTBa). We used 21 Holstein-mixed breed calves, aged between 3 and 15 days with an average weight of 36.8 kg, and housed in pens with troughs for hay, concentrate, and water. The study included two consecutive experimental periods (P1 and P2) of 21 days each, with seven days of adaptation to the diet and facilities. The calves were distributed in a completely randomized design in three treatments with seven repetitions. 1 - Control: 6 L of milk/day during P1 and 6 L of milk/day during P2; 2 – RES (milk restriction): 3 L of milk/day during P1 and 6 L of milk/day during P2; 3 - RES + HMTBa: 3 L of milk/day during P1 and 6 L of milk/day during P2 + 3.3 g of HMTBa/day in both periods. HMTBa was supplied in milk, and the amount of concentrated ration and hay provided and leftovers were recorded daily to estimate dry matter (DM) and crude protein (CP) consumption. Mean daily weight gain (DWG), final weight (FW), and feed conversion (FC) were obtained at the beginning and at the end of each 21-day period. Plasma concentrations of ghrelin and leptin, triglycerides, total protein, urea, lactate, creatinine, alkaline phosphatase, and cholesterol were measured for P1 and P2 at the end of each 21-day period. At the end of P2 animals were slaughtered; sections of the duodenum were collected to evaluate the expression of GHS-R1a and quantity of goblet cells; hypothalamus was used to evaluate the expression of GHS-R1a; rumen was used to evaluate the thickness of epithelium, keratin, density, and height and width of ruminal papillae. In P1, total DM consumption, FW, DWG, glucose and triglycerides were lower in the RES and RES+HMTBa groups (P < 0.001). In P2, there was an improvement in the FC of the RES+HMTBa group (compared to Control and RES) and a lower urea concentration in the RES group (compared to Control and RES+HMTBa) (P < 0.001). No differences were observed among groups regarding hormonal concentrations, histological parameters, and GHS-R1a expression in the duodenum and hypothalamus. Therefore, milk restriction combined with HMTBa supplementation promoted greater compensatory gain by a mechanism independent of changes in GHS-R1a expression and hormone levels of ghrelin and leptin.

Evaluation of nutritional strategies to slow growth rate then induce compensatory growth in 90-kg finishing pigs

Two 44-d experiments were conducted to evaluate nutritional strategies with different concentrations of dietary lysine (and other amino acids) on growth rate and subsequent compensatory gain of 90-kg finishing pigs. Three diets were formulated to contain 0.70 (control), 0.50 and 0.18% standardized ileal digestible (SID) Lys. In Exp. 1, 356 pigs (Line 241 × 600, DNA; initially 89.0 ± 1.10 kg) were used with 4 treatments. From d 0 to 28, pigs received either the control or the 0.50%-Lys diet. On d 28, pigs either remained on these diets or were switched the 0.18%-Lys diet until d 44. There were 18 pens per treatment from d 0 to 28 and 9 pens per treatment from d 28 to 44. From d 0 to 28, pigs fed the 0.50%-Lys diet had decreased (P < 0.001) ADG and G:F compared to those fed the control diet. From d 28 to 44, pigs switched to the 0.18%-Lys diet had decreased (P < 0.05) ADG and G:F compared to pigs that remained on the control or 0.50%-Lys diets. From d 0 to 44, pigs fed 0.50%-Lys diet for 44-d had decreased (P < 0.05) ADG, G:F, and percentage carcass lean compared to pigs fed the control diet. Pigs fed the 0.50%-Lys diet then the 0.18%-Lys diet had decreased (P < 0.05) ADG and G:F compared to other treatments. Pigs fed the 0.50%-Lys diet for 44-d and pigs fed the control diet then 0.18%-Lys diet had decreased (P < 0.05) ADG, G:F, and percentage carcass lean compared to control pigs. In Exp. 2, 346 pigs (Line 241 × 600, DNA; initially 88.6 ± 1.05 kg) were used to evaluate compensatory growth after varying durations of dietary lysine restriction. A total of four treatments were used including pigs fed the control diet for 44-d or fed the 0.18%-Lys diet for 14, 21, or 28-d and then fed the control diet until the conclusion of the experiment on d 44. There were 9 pens per treatment. On average, pigs fed the 0.18%-Lys diet grew 49% slower than the control. Compared to the control, ADG of pigs previously fed the 0.18%-Lys diet increased (P < 0.05) 28% during the first week after switching to the control diet and 12% for the rest of the trial. Despite this improvement, overall ADG, G;F, final BW, and percentage carcass lean decreased (linear, P < 0.05) as the duration of Lys restriction increased. In summary, feeding Lys-restricted diets reduced the ADG and G:F of finishing pigs. Compensatory growth can be induced in Lys-restricted finishing pigs, but the duration of restriction and recovery influences the magnitude of compensatory growth.

96 Cover Crop Grazing and Backgrounding on Carcass Quality

Integration of sheep into cropping systems via cover crop grazing leases has potential to benefit sheep producers with a source of inexpensive, high quality forage. We examined this potential by comparing lamb growth and carcass traits of four rearing systems: grain-finished control (GR), cover crop brassica-finished (CCB), cover crop mixture-finished (CCM), and background on brassica and finished on grain (BK-GR). Dorset x Polypay lambs (n = 60; 3 pens or pastures, 5 lambs each) were blocked by body weight and randomly assigned to treatment. All diets were provided to maximize voluntary dry matter intake. Lambs were harvested after 6 wks of feeding for GR and 8 wks for CCB, CCM and BK-GR (BK-GR = 4 wks brassica then 4 wks grain). Grain-fed lambs (GR and BK-GR, 442 g/d) grew faster than pasture-fed lambs (CCB and CCM, 152 g/d) prior to harvest (Table 1, P < 0.01) and attained greater body mass (HCW), muscling (LEA, EMD), fatness (BF, BWF) and yield grade (all P < 0.05). Growth of pasture-fed lambs declined 38% over time (247 wk 1–4 vs. 152 g/d wk5-8; P < 0.05). Pasture-fed lambs were leaner than grain-fed lambs (BF, yield grade; P < 0.01), yet attained a yield grade 2 average. Background lambs (BK-GR) exhibited a 107% increase in growth when fed grain (232 g/d pasture vs. 481 g/d grain, P < 0.01) and were fatter (BF, P < 0.05) yet had reduced eye muscle depth (P < 0.01) at harvest than GR lambs. Lambs did not differ in growth or any carcass measurement according to pasture type (CCB vs. CCM). We conclude that 8 wks of cover crop finishing produced acceptable carcass weight and finish. Backgrounding on cover crops followed by 4 wks of grain finishing results in marked compensatory gain with lambs achieving the same carcass size and similar qualities to lambs fed only grain.

Influence of ractopamine hydrochloride and days on feed on feedlot performance and red meat yield in thin cull beef cows targeted for a lean market

Thin, beef, cull cows [n = 144; initial body weight (BW) = 465.8 ± 56.9 kg, initial body condition score (BCS) = 2.13 ± 0.68] were serially slaughtered to evaluate the relationship between ractopamine hydrochloride (RH) administration and days on feed (DOF) on feedlot performance and carcass cutout value in a lean cow market. Cows were organized into a 3 × 2 factorial arrangement of treatments (48 pens, 8 pens per treatment, 3 cows per pen) and blocked by BW nested within pregnancy status. Treatment pens were top-dressed 400 mg per cow per day of RH (Actogain 45; Zoetis, Parsippany, NJ) for the final 28 d prior to slaughter to cows spending 28, 42, or 56 DOF. Pen served as the experimental unit, for all calculations. No RH × DOF interactions were detected (P ≥ 0.11), indicating that despite a majority of compensatory gain occurring during the first 28 d of the trial, the magnitude of the RH response was not affected by DOF. Compared to controls, RH incited improvements in feedlot performance, but had a greater extent on carcass weight gain and efficiency. Specifically, RH improved average daily gain (ADG) by 13.7% (P = 0.04) and carcass ADG by 16.9% (P = 0.02) Cattle fed RH displayed a 15.5% improved gain to feed ratio (P = 0.02) and a 20% improved carcass gain to feed ratio (P = 0.05). Inclusion of RH in the finishing diet increased hot carcass weight by 4.5% (P = 0.05; 12.9 kg). However, supplementation of RH did not alter red meat yield (P ≥ 0.16), but provoked a 11.1% improvement in lean maturity (P < 0.01). Evaluation of the main effect of DOF provided insight into the compensatory state of beef cull cows on a high-concentrate diet. Serial slaughter offal weights presented confounding results. With additional DOF, a numerical increase in liver weights (P = 0.20) suggested that organ tissue replenishment occurred throughout the trial, and cattle experienced compensatory gain during the entire feeding phase. In contrast, lung and heart weights were not altered, while kidney tended to decrease linearly (P = 0.08) despite additional DOF. Furthermore, extending DOF generated a linear increase in dry matter intake (P < 0.01) yet a tendency for a decline in ADG (P = 0.10), reinforcing the premise that most of compensatory gain occurred during the first 28 d of the trial. If thin (BCS ≤ 4), healthy candidates can be finished, feeders can reap the benefits of an additive relationship between compensatory gain and RH.

Influence of dietary roughage level and Megasphaera elsdenii on feedlot performance and carcass composition of thin cull beef cows fed for a lean market

One hundred forty-four cull cows (body condition score = 2.10 ± 0.61; BW = 456 ± 47 kg) were organized into a 2 × 2 factorial design (48 pens, 12 pens/treatment, and 3 cows/pen) to evaluate the effect of dietary roughage level and oral drenching of Megasphaera elsdenii NCIMB 41125 (M. elsdenii culture; Lactipro Advance; MS Biotec Inc., Wamego, KS) on performance and carcass characteristics. Cattle were finished over a 42-day realimentation period, and aggressively stepped up over a 10-day period to either a high roughage finisher (HRF; 25% roughage) or a low roughage finisher (LRF; 10% roughage). Within diet, cattle were administered no probiotic or 100 mL of M. elsdenii culture (M. elsdenii NCIMB 41125, 2 108 cfu/mL) on day 0. No diet × probiotic interactions were detected (P ≥ 0.15), suggesting that the magnitude of the response was not influenced by the concentrate level of the diet. The main effect of diet triggered several significant responses. Decreasing roughage level tended to improve average daily gain (ADG) by 9.7% (0.26 kg, P = 0.08), while decreasing dry matter intake (DMI) by 0.9 kg (P = 0.09), provoking a 19.7% enhancement of feed efficiency (0.036 units, P < 0.01). However, interim data revealed declines of performance parameters among both diets with a significant difference between treatments only documented during the final phase of the realimentation period. During the final 14 days, LRF posted a 0.68 kg increase in ADG (P = 0.05) and a 2.0 kg decrease in DMI (P = 0.01), translating to improved feed efficiency (0.054 units, P = 0.03). This suggests that increasing the caloric density of finishing diets may help offset the regression of performance typically observed following a compensatory gain. No carcass traits were impacted by either diet or M. elsdenii culture (P ≥ 0.08). Overall, oral drenching of M. elsdenii culture tended to augment ADG (0.26 kg, P = 0.08) and carcass ADG (0.20 kg, P = 0.10). Implying that M. elsdenii culture was effective at alleviating the acidosis risk prompted by the rapid step-up period employed in the trial and may help capitalize on the narrow timeline of compensatory gain in cull cow realimentation.

Development of digestive organs of female broilers under varying post-hatch fasting times

This study aimed to evaluate the effect of post-hatch fasting time on the weights of body and digestive organs of chicks. Fertile eggs from 62-week-old broiler breeders (Cobb Fast lineage) were incubated and, after hatching, female chicks were randomly divided into six treatments, which corresponded to fasting periods (0, 6, 12, 24, 48, and 72 hours), with 40 chicks per treatment. At 01, 03, 06, and 10 days after hatching, measurements of body weight; residual yolk weight; relative weights of proventriculus + gizzard, intestine + pancreas and liver; and intestine total length were made. At 6 days of age, the chicks submitted to post-hatch fasting, for up to 12 hours, demonstrated greater development, with body weights higher than the other birds. Yet, when fed, no compensatory gain was observed and, at 10 days of age, the birds submitted to 48- and 72-h fasting remained with a lower body development. Intestine growth was also compromised by post-hatch fasting, being reduced in both weight and length. A post-hatching fasting of up to 24 hours did not interfere with the weights of body and digestive organs of 10-day-old female broiler chickens. However, 48- and 72-h post-hatch fastings affected adversely the weight and growth of digestive organs in the birds.