Effects of including Sweet Bran or modified distillers grains in the diet of feedlot steers and sorting at terminal implant on growth performance, feeding behavior, and liver abscess occurrence.

The objectives were to assess the effects of dietary Sweet Bran (Cargill Corn Milling, Blair, NE) on performance and feeding behavior of feedlot steers and determine if terminal implant pen sorting affects performance, feeding behavior, and liver abscess (LA) rate. Two hundred sixteen Angus-cross steers (253 ± 18 kg) were stratified by body weight (BW) to 36 pens. From d 0 to 60, diets contained 40% Sweet Bran (SWBR) or 25% modified distiller's grains and 15% dry rolled corn (MOD; n = 18 pens/treatment). On d 60, steers began transition within treatments to finishing diets containing 25% Sweet Bran or 25% modified distiller's grains (MDGS). On d 111, half of the pens for each dietary treatment were re-stratified by BW to pens (SORT) while the other half were returned to original pens (NOSORT; n = 9 pens/treatment). Steer BW and pen dry matter intake (DMI) were recorded monthly. Rate of feed disappearance was determined on d 5/6, 53/54, 104/105, and 117/118. Pen was the experimental unit for all analyses. The model included the fixed effect of diet for all pre-sort analyses; post-sort analyses included the fixed effects of diet, sort, and the interaction and the random effects of pen and the interaction of diet and pen. On d 60, SWBR had greater BW than MOD (P = 0.05), and SWBR had a greater average daily gain (ADG) from d 0 to 60 (P = 0.05). Though there were no differences after d 28, SWBR had greater DMI d 0 to 28 (P = 0.05). From d 60 to 88, SWBR tended to have lesser ADG than MOD (P = 0.09). Post-sort (d 111 to 196), SWBR tended to have lesser ADG than MOD (P = 0.06), and SORT had a greater rate of feed disappearance than NOSORT (d 117/118; P = 0.01); there were no differences on other dates (Diet: P ≥ 0.38). For final BW, there was a tendency for MOD to be greater than SWBR, and SORT tended to be greater than NOSORT (Diet: P = 0.06; Sort: P = 0.10). Pre- and post-sort ruminal pH had no treatment by day differences (P ≥ 0.77). LA incidence averaged 25%, though rate was not affected by diet, sorting, or the interaction (P ≥ 0.16). Overall, there were no dietary differences in feed disappearance rates, though SORT steers had greater rate of feed disappearance than NOSORT steers on d 117/118. Nominal differences in feeding behavior were noted and including Sweet Bran in the diet was beneficial in the growing period as cattle adjusted to the feedlot.

Effect of increasing zinc supplementation on post-transit performance, behavior, blood and muscle metabolites, and gene expression in growing beef feedlot steers.

Fifty-four Angus-cross steers (297 kg ± 12) were stratified by body weight (BW) to pens (six steers per pen) to determine the effects of supplemental Zn on posttransit growth performance and blood and muscle metabolites. Dietary treatments started 25 d before trucking: control (CON; analyzed 54 mg Zn/kg DM), industry (IND; CON + 70 mg supplemental Zn/kg DM), and supranutritional Zn (SUPZN; CON + 120 mg supplemental Zn/kg DM). Supplemental Zn was bis-glycinate bound Zn (Plexomin Zn; Phytobiotics North America, Cary, NC). On day 0, steers were loaded onto a commercial trailer and transported in 18 h (1,822 km). Individual BW was recorded on days -26, -25, -1, and 0 (pre-transit), 1 (posttransit), 6, 27, and 28. Blood was collected on days -1, 1, 6, and 27. Longissimus thoracis biopsies were collected on days -1, 1, and 28. Daily individual feed disappearance was recorded via GrowSafe bunks. Data were analyzed using Proc Mixed of SAS with fixed effect of diet and steer as the experimental unit (growth performance, blood: n = 18 steers per treatment; muscle: n = 12 steers per treatment). Individual initial BW was used as a covariate in BW analysis. Contrast statements to test linear, quadratic, and Zn effects were used to analyze performance and blood parameters. Repeated measures analysis was used for posttransit DMI recovery and weekly posttransit DMI and Zn intake with the repeated effect of time. MetaboAnalyst 5.0 was utilized for statistical analysis of day 1 (off truck) muscle metabolites. Plasma Zn linearly increased due to Zn on days 1, 6, and 27 (P = 0.01), and off-truck (day 1) serum lactate increased over day -1 by 20%, 0%, and 20% in CON, IND, and SUPZN, respectively (Quadratic: P = 0.01). Muscle lactate tended to increase posttransit in CON and IND (P ≤ 0.07) but not SUPZN. Muscle metabolites relating to amino acid and nitrogen metabolism were increased in all treatments posttransit (P ≤ 0.02), and alanine-glucose cycle metabolites tended to increase in CON and IND (P ≤ 0.07). Steers supplemented with Zn recovered pretransit DMI quicker than CON (by d 2: P = 0.01), while IND had greater overall posttransit DMI than CON with SUPZN intermediate (P = 0.04), and Zn-fed steers had greater ADG posttransit (P = 0.04). Zinc supplementation mitigated muscle or serum lactate increases due to transit and increased posttransit ADG.

Transportation is an inevitable event in the lives of beef cattle, but practical management strategies could mitigate negative effects of transit on growth performance and cattle welfare. This study investigated the effects of dietary zinc prior to and after trucking on growth performance and blood and muscle metabolites of steers after an 18-h transit event. Steers fed supplemental zinc had better feed intake and growth after transit than steers not fed supplemental zinc. Muscle metabolites relating to energy metabolism were greater posttransit in all steers regardless of treatment. Interestingly, blood and muscle lactate, an indicator of muscle fatigue, was decreased in zinc-fed steers. Supplementing zinc prior to trucking may help mitigate muscle fatigue and improve cattle welfare during the receiving period.

Long-duration transit and food and water deprivation alter behavioral activities and aggressive interactions at the feed bunk in beef feedlot steers.

The objective of these experiments was to assess the effects of food and water deprivation and transit duration on the behavior of beef feedlot steers. In Experiment 1, 36 Angus-cross steers (353 ± 10 kg) were stratified to 6 pens and assigned one of three treatments (n = 12 steers per treatment): control (CON; stayed in home pens with ad libitum access to feed and water), deprived (DEPR; stayed in home pens but deprived of feed and water for 18 h), or transported (TRANS; subjected to 18-h transit event and returned to home pens). In Experiment 2, 60 Angus-cross steers (398 ± 5 kg; 6 steers per pen) were transported either 8 (8H) or 18 (18H) h. Four 8H pens (n = 24 steers) and six 18H pens (n = 36 steers) were used for behavioral analysis. In both experiments, the time to eat, drink, and lay down was recorded for each steer upon return to home pens. Total pen displacements from the feed bunk were also assessed for the 2 h following feed access in both experiments. Data were analyzed using Proc Mixed of SAS 9.4, with treatment as a fixed effect. Steer was the experimental unit for behavioral activities, while pen was the experimental unit for bunk displacements. Displacements were analyzed as repeated measures with the repeated variable of time. In Experiment 1, the time to eat and drink was similar across treatments (P ≥ 0.17). However, TRANS laid down in 16.5 min while DEPR did not lay down until 70.5 min post-arrival to pen (P < 0.01). Deprived steers had greater bunk displacements in the first 70 min post-feed access than CON or TRANS, though displacements among treatments from 100 to 120 min post-feed access were similar (treatment × time: P = 0.02). In Experiment 2, both 8H and 18H steers laid down approximately 25 min post-home pen arrival (P = 0.14). There was no effect of transit duration or duration by time on bunk displacements (P ≥ 0.20), though displacements were greater from 0 to 20 min than from 20 to 30 min post-feed access (time: P = 0.04). Steers that were deprived of feed and water were highly motivated to access those resources, while transported steers prioritized laying down. Producers should consider these priorities when preparing to receive cattle from a long transit event.

Because of the segmentation of the cattle industry, cattle are transported at least once during their lives. The objective of these two studies was to determine if transportation, feed and water deprivation, and/or transit duration changed the behavior of feedlot steers. The first study found steers transported for 18 h preferred to lay down instead of competing for food, unlike steers that were deprived of food and water for 18 h. Bunk displacements were also increased in steers deprived of food and water, indicating increased aggression. In the second study examining effects of transit duration (8 vs. 18 h), steers from both treatments laid down within 25 min of arrival back to the home pens. There were no differences in the frequency of bunk displacements between treatments. Producers should consider the increased motivation for cattle to lay down after transportation and the increased aggression at the feed bunk in food-deprived cattle when developing post-arrival management strategies.

Dietary zinc concentration and lipopolysaccharide injection affect circulating trace minerals, acute phase protein response, and behavior as evaluated by an ear-tag-based accelerometer in beef steers.

To assess plasma trace mineral (TM) concentrations, the acute phase protein response, and behavior in response to a lipopolysaccharide (LPS) challenge, 96 Angus cross steers (average initial body weight [BW]: 285 ± 14.4 kg) were sorted into two groups by BW (heavy and light; n = 48/group), fitted with an ear-tag-based accelerometer (CowManager SensOor; Agis, Harmelen, Netherlands), and stagger started 14 d apart. Consecutive day BW was recorded to start the 24-d trial (days -1 and 0). Dietary treatments began on day 0: common diet with either 30 (Zn30) or 100 (Zn100) mg supplemental Zn/kg DM (ZnSO4). On day 17, steers received one of the following injection treatments intravenously to complete the 2 × 3 factorial: 1) SALINE (~2-3 mL of physiological saline), 2) LOWLPS: 0.25 µg LPS/kg BW, or 3) HIGHLPS: 0.375 µg LPS/kg BW. Blood, rectal temperature (RT), and BW were recorded on day 16 (-24 h relative to injection), and BW was used to assign injection treatment. Approximately 6, 24 (day 18), and 48 (day 19) h after treatment, BW, RT, and blood were collected, and final BW recorded on day 24. Data were analyzed in Proc Mixed of SAS with fixed effects of diet, injection, diet × injection; for BW, RT, dry matter intake (DMI), plasma TM, and haptoglobin-repeated measures analysis were used to evaluate effects over time. Area under the curve analysis determined by GraphPad Prism was used for analysis of accelerometer data. Body weight was unaffected by diet or injection (P ≥ 0.16), but there was an injection × time effect for DMI and RT (P < 0.05), where DMI decreased in both LPS treatments on day 16, but recovered by day 17, and RT was increased in LPS treatments 6 h post-injection. Steers receiving LPS spent less time highly active and eating than SALINE (P < 0.01). Steers in HIGHLPS spent lesser time ruminating, followed by LOWLPS and then SALINE (P < 0.001). An injection × time effect (P < 0.001) for plasma Zn showed decreased concentrations within 6 h of injection and remained decreased through 24 h before recovering by 48 h. A tendency for a diet × time effect (P = 0.06) on plasma Zn suggests plasma Zn repletion occurred at a greater rate in Zn100 compared to Zn30. These results suggest that increased supplemental Zn may alter the rate of recovery of Zn status from an acute inflammatory event. Additionally, ear-tag-based accelerometers used in this study were effective at detecting sickness behavior in feedlot steers, and rumination may be more sensitive than other variables.

Effect of bis-glycinate bound zinc or zinc sulfate on zinc metabolism in growing lambs.

To assess the efficacy of bis-glycinate bound Zn, 36 crossbred wethers (34 ± 2 kg) were sorted by body weight into three groups and stagger started on a Zn-deficient diet (18 mg Zn/kg dry matter [DM]; 22.5% neutral detergent fiber [NDF]) for 45 d prior to a 15-d metabolism period (10 d adaptation and 5 d collection). On day 46, lambs were randomly assigned to dietary treatments (four lambs treatment-1group-1): no supplemental Zn (CON) or 15 mg supplemental Zn/kg DM (ZINC) as Zn sulfate (ZS) or bis-glycinate (GLY; Plexomin Zn, Phytobiotics). Blood was collected from all lambs on days 1, 44, 56, and 61. Liver, jejunum, and longissimus dorsi samples were collected after euthanasia on day 61. Gene expression was determined via quantitative real-time polymerase chain reaction. Data were analyzed using ProcMixed of SAS (experimental unit = lamb; fixed effects = treatment, group, and breed) and contrast statements assessed the effects of supplemental Zn concentration (ZINC vs. CON) and source (GLY vs. ZS). After 15 d of Zn supplementation, plasma Zn concentrations were greater for ZINC vs. CON and GLY vs. ZS (P ≤ 0.01); tissue Zn concentrations were unaffected (P ≥ 0.27). Liver Cu concentrations were lesser for ZINC vs. CON (P = 0.03). Longissimus dorsi Mn concentrations were greater for ZINC vs. CON (P = 0.05) and tended to be lesser for GLY vs. ZS (P = 0.09). Digestibility of DM, organic matter (OM), and NDF was lesser for ZINC vs. CON (P ≤ 0.05); acid detergent fiber digestibility tended to be greater for GLY vs. ZS (P = 0.06). Nitrogen retention (g/d) tended to be greater for GLY vs. ZS (P = 0.10), and N apparent absorption was lesser for ZINC vs. CON (P = 0.02). Zinc intake, fecal output, retention, and apparent absorption were greater for ZINC vs. CON (P ≤ 0.01). Apparent absorption of Zn was -5.1%, 12.8%, and 15.0% for CON, ZS, and GLY, respectively. Nitrogen and Zn retention and apparent absorption were not correlated for CON (P ≥ 0.14) but were positively correlated for ZINC (retention: P = 0.02, r = 0.52; apparent absorption: P < 0.01, r = 0.73). Intestinal expression of Zn transporter ZIP4 was lesser for ZINC vs. CON (P = 0.02). Liver expression of metallothionein-1 (MT1) tended to be greater for GLY vs. ZS (P = 0.07). Although Zn apparent absorption did not differ between sources (P = 0.71), differences in post-absorptive metabolism may be responsible for greater plasma Zn concentrations and liver MT1 expression for GLY-supplemented lambs, suggesting improved bioavailability of GLY relative to ZS.

Effect of rumen-protected lysine on growth performance, carcass characteristics, and plasma amino acid profile in feedlot steers.

The objective of this study was to evaluate growth performance, carcass characteristics, and plasma amino acid profiles of feedlot steers fed rumen-protected Lys. Forty-two Angus-cross steers (304 ± 25 kg) were blocked by weight and fed treatment diets for 180 d (growing days 0 to 55; finishing days 56 to 180): 1) Lys-deficient diet (CON; n = 12 steers), 2) Lys-adequate diet containing soybean meal (POS; n = 12 steers), or 3) Lys-deficient diet plus supplemental rumen-protected Lys (RPL; AjiPro-L; Ajinomoto Animal Nutrition North America, Eddyville, IA; n = 18 steers). Consecutive day bodyweights (BWs) were recorded to begin and end growing and finishing. Individual steer dry matter intake (DMI) was recorded. Blood was collected on days 0, 56, and 179 for analysis of physiological free amino acids. Steers were harvested on day 180 and carcass characteristics were recorded. Data were analyzed using Proc Mixed of SAS 9.4. Steer was the experimental unit and treatment was the fixed effect for all parameters. Block was a fixed effect for growth performance, feed intake, and carcass data. The day 0 value for each parameter of physiological free amino acids was used as a covariate during analysis. The CON steers had greater BW, average daily gain (ADG), and gain to feed (G:F) at the end of growing (day 56; P ≤ 0.05) vs. POS and RPL. The CON steers also had greater final BW (P = 0.04) and overall ADG (P = 0.04) than RPL, while POS was intermediate. Carcass characteristics were not different across treatments [hot carcass weight, dressing percent, ribeye area, back fat, kidney/pelvic/heart (KPH) percent, marbling, or calculated yield grade; P ≥ 0.13]. Plasma urea N was greater in POS steers on days 56 and 179 (P ≤ 0.04). Plasma Lys and Arg concentrations were greater in POS at day 56 (P ≤ 0.02); however, there was no difference among treatments for these two variables at day 179 (P ≥ 0.44). Steers in all treatments had greater DMI than predicted, causing a negative metabolizable Lys balance for all treatments during growing. Though the metabolizable Lys balance was positive for POS and RPL-fed steers during finishing, the increased metabolizable Lys in these treatments may have decreased performance if other amino acids were imbalanced due to increased intakes.