<p> There have been many changes in the United States sheep industry over the years. Decreasing profitability of wool production has shifted the focus of many producers to strictly meat production. In south Texas, extreme high summer temperatures add an additional challenge in raising wool breeds of sheep. Hair sheep are gaining popularity in lamb-only production systems as they are more adapted to hot climates and eliminate shearing costs. The Dorper is the most popular breed of hair sheep throughout Texas due to superior lamb carcasses. Maximizing reproductive efficiency is critical for increasing the profitability of sheep production. Accelerated lambing systems can produce 3 lamb crops every two years versus 1 lamb crop per year. For this to be accomplished, ewes must be capable of breeding early post-partum and at all times of the year. We determined the reproductive characteristics of Dorper ewes. In the absence of a ram, Dorper ewes were anestrous from March until May. We observed considerable variation of ewes when both entering and ending anestrous. During the initial breeding season, 7-d CIDR^&reg; treated ewes, which conceived 1^st service, had a significantly lower mean day of birthing (3.2 &plusmn; 2.1 d) compared to (10.1 &plusmn; 1.9 d) control ewes, resulting in a shorter lambing duration. During the seasonal anestrous period both CIDR^&reg; treated and control post-partum Dorper ewes were stimulated to ovulate while in the presence of the ram. However, during this time, 9-d CIDR^&reg; treatment significantly shortened both overall ram to lambing interval (152.8 &plusmn; 3.2d vs.165.7 &plusmn; 3.0 d) and first service ram to lambing interval (149.3 &plusmn; 1.3 d vs. 160.7 &plusmn; 1.5 d). Fall-born Dorper ewes with known birth dates had a mean age of puberty of 306.5 &plusmn; 4.9 d. Fall-born yearlings and spring-born ewe lambs were exposed to a ram during the first fall breeding season following their birth. While no difference was found in overall conception rate, fall-born yearlings had a significantly greater first service conception rate (83.3 %) compared to spring-born lambs (28.6 %). The findings of this study illustrate that Dorper ewes have the potential to be utilized in accelerated lambing systems in south Texas. By achieving a high conception rate post-partum simultaneous to the anestrous season, we were able to maintain an 8 mo lambing interval during the first two breeding season. We conclude that the reproductive attributes of the Dorper ewe makes them an excellent choice for sheep producers throughout South Texas.</p>

The systematic status of whitefishes endemic to Bear Lake, Utah- Idaho, has remained tenuous since t heir original description. Clarification of this problem was the major objective of the present study. The general approach was an integrated one, including examination of morphological, biochemical and ecological parameters; artificial hybrids were produced and compared with questionable groups from the natural population. Morphological analysis revealed five forms of Bear Lake whitefishes. Prosopium gemmiferum (Bonneville cisco) and !· abyssicola (Bear Lake whitefish) were well differentiated from other forms and were treated as originally described. The P. spilonotus (Bonneville whitefish) group, however, was found to be made up of two morphologically distinct populationa, referred to as P. spilonotus (small form) and !· spilonotus (large form). The fifth group referred to as!· gemmiferum-like (represented by only five specimens) was intermediate between!· gemmiferum and either P. spilonotus (small form) or !· abyssicola and was hypothesized to be of hybrid origin. Mul tiple discriminant function analysis of the four major groups and ~· williamson! (mountain whitefish) (Logan River) confirmed morphological differentiation between forms . Hybridization studies among Bear Lake Prosopium and P. williamson! involved 50 homo- and hetero specific crosses (17 combinations). Of 12 experimental hybrid combinations attempted , all those involving simul taneously ripe specimens of two groups (five crosses) showed maximum fertilization success equalling that of pure crosses. No evidence that interspecific crosses are l ess successful than conspecific crosses, with the possible exception of ~· williamson! ~ x ~· gemmiferum d (W x G), was obtained. Culture methods were developed and morphological comparisons made. Origin of ~· gemmiferum-like hybrids in the lake population was not consistently explained by morphological comparison of known ~· spilonotus (small form) ~ x ~· gemmiferum d (S x G) hybrids or ~· abyssicola 'i' x ~· gemmiferum d (A x G) hybrids; morphometric characters were more like S x G hybrids while meristic characters were more closely associated with A x G hybrids. Based on evidence available, no definitive statement could be made concerning the origin of ~· gemmiferum-like hybrids except that they are hybrids among combina tions of~· gemmiferum and either P. spilonotus (small form) or ~· abyssicola. No known hybrid explained the origin of either group of ~· spilonotus . Electrophoretic analysis of general proteins and several enzyme systems of various tissues showed much similarity among Bear Lake Prosopium; only ~· williamsoni was totally unique. Biochemical evidence did not support or refute separate consideration of the two forms of ~· spilonotus but did establish that neither were phenotypic variants of ~· williamson!. Ecological characteristics of Bear Lake Prosopium revealed important distinctions between forms. Growth histories of ~· abyssicola, ~· spilonotus (small form) and ~· spilonotus (large form) showed pronounced differences. Distinct differences in growth and in age and size at maturity of forms of ~· spilonotus provided further evidence supporting their separate consideration. Spatial overlap of spawning activities was marked between forms of ~· spilonotus and ~· gemmiferum; ~· abyssicola was well separated spatially. Temporally, slight overlap was observed between ripe females of one group and ripe males of the succeeding group · to spawn. The only observation of the simultaneous occurrence of ripe females of two forms was between ~· spilonotus (large form) and P. spilonotus (small form); in this instance, the number of ripe females of each form was extremely small. No evidence of mass hybridization among forms was observed. A combination of temporal, spatial and ethological premating isolating mechanisms are thought to be important in reproductive isolation of Bear Lake whitefishes while postmating mechanisms are nonfunctional with the possible exception of hybrid sterility. Morphological and ecological analyses, combined with results of experimental hybridization, provided abundant evidence supporting separate recognition of the two forms of ~· spilonotus. Karyotypes of P. gemmiferum, ~· abyssicola and ~· spilonotus (small form) have been determined (Booke, 1974) and are unique for each species. If the karyotype of P. spilonotus (large form) is found to also be unique, there should be no question that the two forms of ~· spilonotus represent distinct species. Final clarification of the taxonomic status of these forms will not come until karyotype data is available; however, based upon present evidence, tentative recognition of a new species is recommended.

<p> Heat stress is a physiologic state where an animal can no longer properly regulate it&rsquo;s body temperature to prevent hyperthermia. It has been well documented that heat stress can negatively impact feed intake, growth performance, carcass characteristics, gut morphology and integrity in swine. Finishing swine are particularly sensitive to heat stress which costs the U.S. swine industry millions of dollars annually. There are several ways heat challenges can be mitigated to reduce the negative impacts of heat stress during warmer temperatures, one of which being nutrition. Knowing that heat stress alters intestinal barrier function and morphology, we took a holistic approach in assessing how supplementing finishing pigs with an inorganic zinc source and an organic/inorganic zinc blend during cyclic heat stress could potentially improve gut function and thus growth performance and carcass characteristics. </p><p> Six hundred cross-bred pigs were housed under thermoneutral (TN) or cycling heat (HS) conditions simulating summer heat with acute 3-day heat waves for a 70-day study. Thermoneutral conditions were 18.9&ndash;16.7 &deg;C throughout the study. Heat stress pigs were housed at the same temperature as TN from d 0&ndash;18, then increasing temperatures d 18&ndash;21 (28 &deg;C/24 &deg;C for 12h:12h, 50.0% humidity) followed by 30 &deg;C/26.7 &deg;C (12h:12h, 52.4% humidity) d 24&ndash;70 except during acute heat (32&ndash;33 &deg;C/29&ndash;30 &deg;C, 12h:12h, 51.5% humidity) on d 21&ndash;24, 42&ndash;45, and 63&ndash;66. Treatments were arranged in a 2&times;6 factorial with main effects of environment (HS vs. TN) and six dietary zinc supplementations, from either an inorganic (ZnO) or organic (Availa^&reg;Zn) source. Dietary Zn treatments were: 1) 50 mg/kg ZnO; 2) 130 mg/kg ZnO: 3) 50 mg/kg organic Zn; 4) 50 mg/kg ZnO + 40 mg/kg organic Zn; 5) 50 mg/kg ZnO + 60 mg/kg organic Zn; and 6) 50 mg/kg ZnO + 80 mg/kg organic Zn. Pigs (5/pen) were blocked by initial BW (72.2 kg) and randomly allotted to 1 of 12 temperature and diet treatment combinations across 10 replicates. There were 5 rooms per thermal environment, each containing 2 blocks of dietary treatments. Body weight and feed intake were determined at the beginning/end of each acute and chronic heat event. All pigs were ultrasonically scanned at the 10^th rib for loin eye area (LEA) and backfat (BF) to calculate percent lean on d 63. Pigs were marketed on d 64 (TN) and d 71 (HS). Growth performance, carcass characteristics, and gut morphology were analyzed by the MIXED procedure and gene expression was anazlyzed with the GLM procedure in SAS 9.4. At d 63, HS pigs were lighter (124.11 vs. 128.34 kg; <i>P</i> &lt; 0.001), had lower overall ADG (826 vs. 901 g/d; <i> P</i> &lt; 0.001), ADFI (2.740 vs. 3.032 kg/d; <i>P</i> &lt; .001), but tended to have greater G:F (0.301 vs. 0.297; <i>P</i> = 0.1204). A diet by environment interaction was noted for overall ADG (<i> P</i> = 0.0039) and ADFI (<i>P</i> &lt; 0.001). The interaction is an order of magnitude in the reduction of ADG as a result of diet 5 having only a 3.9% reduction in ADG whereas diet 6 had 14.4% reduction in ADG under HS conditions. Pigs under HS had less BF at the 10th rib (16.9 vs. 18.0 mm; <i> P</i> &lt; 0.001) and a smaller LEA (53.5 vs. 55.2 cm²; <i> P</i> &lt; 0.001), but a greater calculated percent lean (54.6 vs. 54.1%; <i> P</i> = 0.039). Overall, HS pigs used 6.13 L more water per day than TN pigs (<i>P</i> = 0.0007) with the biggest difference in water utilization during the d 42&ndash;45 acute heat wave (6.17 vs. 15.6 L/pig/day; <i> P</i> &lt; 0.0001). Cyclic heat stress simulating summer conditions reduced growth performance by approximately 8.3%, resulting in 4 kg lighter pigs after 63d. </p><p> To explore how zinc supplementation impacted gut morphology and jejunal gene expression during cyclical HS, one pig/pen (n = 80) from diets 1, 2, 3, and 6 from each environment was harvested on d 65 at the Purdue University meats lab. Intestinal tissue was collected and analyzed for gene expression (heat shock proteins (HSP) 27, 70, and 90, occludin, and mucin-2) and morphology (n = 80). Ileal villi were shorter in HS pigs (<i>P</i> = 0.020) and jejunal HSP70 (<i>P</i> &lt; 0.080) also tended to increase with HS. A 3-way interaction (Environment x Zn Source x Zn Level) was observed for villus height (<i>P</i> &lt; 0.02) and HSP27 (<i>P</i> = 0.05) expression in the jejunum. The villus height 3-way interaction was primarily caused by the 50 mg/kg inorganic Zn treatment increasing villus height under HS and all other treatments decreasing villus height under HS. (Abstract shortened by ProQuest.) </p><p>

<p> The study objective was to evaluate the effects of vaccination (respiratory and clostridial vaccination or no vaccination) and deworming (fenbendazole and levamisole or no deworming) of high risk stocker calves on-arrival on health and growth performance. Eighty sale barn origin calves were purchased three separate years (n = 240) from local order buyer. Steers (n = 61) and bulls (n = 179) were received over three days (d &ndash;3 to &ndash;1). On d 0 calves were stratified by arrival BW and FEC into 20 pens of 4 calves each, and treatment was applied to pens in 2 x 2 factorial. Vaccination increased the likelihood of BRD 1.7 times (P = 0.07) versus calves not vaccinated. Vaccination did not affect gain, but calves receiving dewormer had greater ADG than those not receiving dewormer. Calves that arrived uncastrated or with high fever (&ge; 40.0 &deg;C) gained less and were 1.7 and 4.3 times more likely (P &lt; 0.10) to be treated for disease, respectively.</p><p>

<p> Dry lots, or small paddocks bare of vegetation, are commonly used to manage over- conditioned equids in order to restrict the diet by offering hay lower in digestible energy and non-structural carbohydrates (NSC) compared to unrestricted pasture access. However, the lack of vegetation in dry lots often caused by overgrazing and heavy traffic has been associated with negative environmental impacts such as soil erosion. Turfgrasses may be suitable as ground cover in dry lots because they are tolerant of traffic and close mowing (e.g. grazing) and may be low to moderate in both yield and NSC. The objective of this body of work was to 1) characterize the prevalence of over-conditioned equids in MD and whether dry lots were being used for their management, and 2) to assess the relative traffic tolerance, nutritional composition, and palatability of commercially available seeded cultivars of cool- season (CS) and warm-season (WS) turfgrasses for their potential use on horse farms. An online survey of licensed stable operators revealed that ~ 40% of horses in MD were over-conditioned and feeding hay in dry lots was a preferred practice despite requiring more maintenance and management time. Two additional studies evaluating wear tolerance of 8 CS and 6 WS cultivars exposed to either no, low, or high simulated horse traffic found that soil compaction increased as treatment level increased in CS and WS traffic trials (<i>P</i> &lt;0.0001). Persistence was reduced in response to traffic in CS cultivars (<i>P</i> = 0.0003), but not in WS cultivars. Overall, tall fescue and zoysiagrass cultivars were most traffic tolerant, but only zoysiagrass had a more ideal NSC concentration. In the final study, horses exhibited no grazing preference among CS cultivars, whereas among WS cultivars they prefered common bermudagrass and crabgrass (<i>P</i> &lt; 0.02). Several cultivars, including Maestro and Regenerate tall fescue, Zenith zoysiagrass, and Riviera bermudagrass cultivars were closest to meeting desired goals of being traffic tolerant, moderate in yield, and relatively low in NSC, and are thus recommended to be evaluated in future studies for on-farm persistence in dry lots and heavy use areas and for long-term effects of grazing by equids. </p><p>

<p> The overall objective of this study was to determine if the level of growth promotant technology used among production systems influence animal and carcass performance, meat quality, production economics, the environmental impact, and determine consumer preferences and perception. Angus &KHcy; Simmental steer calves (<i>n</i> =120) were stratified by birth date, birth weight, and dam age in a completely randomized design and assigned to one of four treatments: 1) no antibiotics (NA, receiving no technology); 2) non-hormone treated (NHTC, fed monensin and tylosin); 3) implant (IMPL, administered a series of three implants), and 4) implant plus fed a beta-agonist (IMBA, administered the same implant strategy as IMPL plus, fed ractopamine-HCI for the last 30 d prior to harvest). Animal weight, production expenses, and environmental factor data were collected from the production segments including: cow-calf, backgrounding, and finishing. During the finishing segment, animal feed intake, average daily gain (ADG), and efficiency was obtained. Carcass meat quality and yield performace was assessed. Striploins were collected for analyses post fabrication. Steaks were designated to specific postmortem aging periods, utilized for Warner-Bratzler shear force (WBSF), crude fat, and consumer sensory analyses. The consumer analyses evaluated beef production system information undisclosed and disclosed or simiply, without and later with information to assess palatability only, perception only, and perception plus palatability among untrained consumer panelists. </p><p> IMPL had the greatest (<i>P</i> &lt; 0.01) ADG and gain to feed (G:F). The final calculated body weight and hot carcass weight was similar (<i>P</i> > 0.05) and heavier (<i>P</i> &lt; 0.01) for IMPL and IMBA in comparison to NA and NHTC, which were similar (<i>P </i> > 0.05). The actual branded carcass value was similar (<i> P</i> > 0.01) for NA and IMPL and greater (<i>P</i> &lt; 0.05) than NHTC and IMBA, which was similar (<i>P</i> > 0.05). Excluding the cost of the calf, production costs were similar (<i>P</i> > 0.05) and lowest (<i>P</i> &lt; 0.05) for NA and IMPL, NHTC was intermediate (<i>P</i> &lt; 0.05), and IMBA had the greatest (<i> P</i> &lt; 0.05) production cost. Net return was similar (<i>P</i> > 0. 01) between NA and IMPL, which was greater (<i>P</i> &lt; 0.01) than NHTC and IMBA, which were similar (<i>P</i> > 0.01). In the environmental analysis, IMPL reduced GHG (CO₂e/kg HCW) emissions by 8%, energy use (MJ/kg HCW) by 6%, water use (kg H₂O/kg HCW) by 6%, and reactive N loss (g N/kg HCW) by 6%. The IMBA reduced GHG emissions by 7%, energy use by 3%, and reactive N loss by 1%. </p><p> Meat quality analyses for marbling score and crude fat among NA and NHTC did not differ (<i>P</i> > 0.05) but were greater (<i>P</i> &lt; 0.05) than IMPL and IMBA, which were similar (<i>P</i> > 0.05) and lower in crude fat. Steaks from NA and NHTC did not differ (<i>P </i> > 0.05) for WBSF though were more tender (<i>P</i> &le; 0.05) than IMPL and IMBA, which were similar (<i>P</i> &le; 0.05) and tougher (<i>P</i> &le; 0.05). During the Undisclosed without Meat panel, NA was most preferred (<i>P</i> &le; 0.05) and IMBA was least preferred (<i>P</i> &le; 0.05) while NHTC and IMPL were intermediate and similar (<i>P</i> > 0.05). All samples differed (<i>P</i> &le; 0.05) during the Disclosed with Meat panel where, NHTC was most preferred followed by NA, IMPL, and IMBA. Despite improvements from use of monensin, tylosin, growth promoting implants with and without ractopamine HCl, cattle within IMPL and IMBA resulted in greater animal and carcass weights, were most effective at minimizing the environmental impact, and improved producer net return (IMPL only). However, consumers may have detected reductions in tenderness and palatability as IMPL and IMBA were least preferred. Consumers preferred the palatability of meat raised with judicious use of antimicrobials and antibiotics to ensure animal health when production information was disclosed (NHTC).</p><p>

<p> The objective of this research was to compare different expressions for the digestibility of Ca in both pigs and chickens, and to determine the true total tract digestible (TTTD) Ca requirement for 10- to 20-kg and 20- to 40-kg pigs. </p><p> In the first study, two experiments were conducted to compare apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of Ca in pigs. In Exp. 1, three semi-purified diets with soybean meal, canola meal or sunflower meal as the sole source of Ca were formulated. Eighteen cannulated pigs (initial BW = 66 &plusmn; 5 kg) were assigned in a randomized complete block design to 3 treatments and 6 replicates per treatment. Results indicated that for either Ca or P, the ATTD was not different from AID in three diets. In Exp. 2, diets with four Ca concentrations were formulated with calcium carbonate as the Ca source. Sixteen cannulated pigs (initial BW = 73 &plusmn; 4 kg) were assigned in a randomized complete block design to 4 treatments in 2 experimental periods. The results indicated that the ATTD of Ca was not different from AID for all diets, and the Ca digestibility was not affected by the dietary Ca concentration. The results of these two experiments indicated that both AID and ATTD can be used to describe the digestibility of Ca for growing-finishing pigs. Total tract digestibility was used to express digestibility of Ca in later studies. </p><p> A second series of studies was conducted to decide whether ATTD or TTTD should be used to estimate Ca digestibility of limestone and dicalcium phosphate (DCP). Two pig experiments were conducted to determine the ATTD and TTTD of limestone and DCP, and their additivity in a semi-purified diet for pigs. In Exp. 1, forty eight barrows with an average initial BW of 19.2 &plusmn; 1.1 kg were assigned to 1 of 6 dietary treatments in a 2 &times; 3 factorial arrangement of two Ca sources, including limestone or DCP, with three dietary Ca concentrations each. Diets were fed for a 5-d adjustment period followed by a total collection period of 5 d. The results indicated that the increased dietary Ca concentration linearly increased Ca intake, digested and retained, but did not affect the ATTD of Ca when using limestone and DCP as Ca sources. In Exp. 2, seventy-two barrows with an average initial BW of 20.8 &plusmn; 1.3 kg were used to test the additivity of TTTD for Ca in limestone and dicalcium phosphate (DCP) in pigs. All pigs were assigned to 1 of 9 dietary treatments in a 3 &times; 3 factorial arrangement of three Ca sources, including limestone, DCP, or a mixed diet at a ratio of 1:1; and three dietary Ca concentrations. Feeding and sample collection procedures were as in Exp. 1. The results indicated that the average ATTD were 66.46, 70.34, and 69.32% for limestone, DCP, and their mixed diet, respectively. By regressing daily digested Ca against daily Ca intake, the TTTD of Ca was determined at 70.06, 76.42, and 73.72% for limestone, DCP, and their mixed diet, respectively. The endogenous losses of was estimated to be between 0.217 to 0.321 g/kg DM intake. The predicted TTTD for Ca in the mixed diet of limestone and DCP was calculated to be 72.67% based upon the Ca contribution coefficient of 0.59 for limestone and 0.41 for DCP. The predicted Ca TTTD (72.67%) in the mixed diet was not statistically different from the determined Ca TTTD (73.72%). It is concluded that although ATTD of limestone and DCP were not affected by the Ca concentration in the diet, TTTD is recommended for evaluation of Ca digestibility because of its additivity in a mixed diet. </p><p> A similar additivity experiment was conducted on Ross 708 broiler chickens from d 22 to d 27 post hatch, using true ileal digestibility (TID) for Ca in limestone and dicalcium phosphate (DCP). The birds were fed a standard broiler starter diet from d 1 to 11 post hatching. A total of 504 birds were grouped in a 3 &times; 3 factorial arrangement of 3 Ca sources including limestone, DCP, and their mixed diet at a ratio of 1:1, and 3 dietary Ca concentration at 3.3, 4.3, and 5.3 g/kg. The results showed that by regressing digested Ca per bird against Ca intake per bird, the TID of Ca was determined at 63.73, 67.14, and 67.79% for limestone, DCP, and the mixed diet, respectively. (Abstract shortened by ProQuest.) </p><p>

<p> The effect of feeding corn by-products on cow reproductive performance, as well as offspring growth and reproductive performance has been investigated through four separate studies. The first study was conducted to evaluate the use of dried distiller&rsquo;s grains with solubles (DDGS) in beef cow diets during early lactation on both dam and heifer offspring growth and reproductive performance. Three diets, consisting of 0, 2.5 or 4.7 kg/d DM of DDGS were formulated to be isocaloric but the DDGS diets exceeded protein requirements. Milk production was not different, however, milk components increased with the addition of DDGS. Resumption of cyclicity of dams, as well as days of age at puberty in heifer offspring were not different. However, while not statistically different, time-artificial insemination (TAI) rates of both cow and heifer offspring were numerically improved with the addition of DDGS in the diet. Plasma urea nitrogen (PUN) concentrations in the cows followed the trend of being higher with increasing levels of DDGS. While PUN concentrations did reach levels that are considered detrimental to fertility, they did not seem to have a negative impact on conception.</p><p> In the second study, the use of corn gluten feed (CGF) in dam diets and its effects on their reproductive performance was investigated. Three diets, consisting of 0, 3.3 or 6.7 kg/d DM of CGF were formulated to be isocaloric but the CGF diets exceeded protein requirements. Milk production and milk components were not different with the exception of fat, which tended to be greater in the high CGF treatment. Resumption of cyclicity and TAI conception rates were not improved when CGF was added to the diet. Plasma urea nitrogen concentrations did not approached what would have been considered detrimental to fertility.</p><p> The third study was conducted to evaluate feeding DDGS during the second trimester or the second and third trimester (3.0 or 3.5 kg/d DDGS, respectively), on heifer offspring reproductive performance. Growth performance of heifer offspring did not differ among treatments. There were no differences in TAI conception rates in heifer offspring from dams fed DDGS but, dominant follicles tended to be larger in heifer offspring from dams fed DDGS during the second trimester. Due to the lack of improvement in reproductive performance in this study, it has been hypothesized that lactation may be a more critical time point for improvements in heifer offspring reproductive performance.</p><p> The fourth study followed the hypothesis of the third study. Because heifer offspring reproductive performance was positively impacted when dams were fed DDGS during early lactation, evaluation of dams fed DDGS during early lactation on bull offspring performance was investigated. Bull offspring growth performance was not impacted by dam diets during early lactation. Scrotal circumference, testosterone concentrations and semen analysis were used to evaluate days of age at puberty, however, puberty attainment in bull offspring was also not impacted. In summary, feeding DDGS as a primary source of dietary energy during early lactation had a positive impact on both cow and heifer offspring reproductive performance, but this does not seem to be true for bull offspring.</p><p>

No description available.

No description available.