The main objective of the study was to determine how phase feeding manipulation affects growth performance, feed cost, carcass characteristics and quality of meat from broiler chickens. A total of 180 day old un-sexed broiler chicks (Cobb 500) were separated into 3 dietary treatments of 60 birds per treatment and each treatment was replicated 3 times with 20 birds per replicate. The dietary treatments were as follows: T1 (starter 1-7 days; grower 8-21 days; finisher 22-35 days), T2 (starter 1-14 days; grower 15-21 days, finisher 22-35 days) and T3 (starter 1-14 days; grower 15-28 days; finisher 29-35 days). Feed intake and body weight gains were recorded weekly in kilograms. Average daily gain and feed conversion ratio were computed weekly. At day 35, the chickens were slaughtered and 12 representative breast muscles from each treatment were used for the determination of muscle pH (pH1, pH24 and pH48) and colour coordinates (Lightness – L*, redness – a* and yellowness – b*) in triplicate at 1 hour, 24 hours and 48 hours post-mortem.Feed intake (FI), feed conversion ratio (FCR), average daily gain (ADG) and average body weight at slaughter (ABW) were not significant (P>0.05) amongst the treatments. The most cost efficient feed (which accumulated the cheapest cost feed per kg were) T1 (R11.32) and T3 (R11.32) although there was a slight difference in the gross profit of these treatments T1 (R45.71) and T3 (R44.48). Carcass characteristics were the same (P > 0.05) across the treatments except for the wing, thigh, drumstick and the breast (P < 0.05). T2 had the highest wing weight (166.63±8.60), T1 (113.03±8.60) and the lowest in T3 (74.46±8.60). The thigh weight were greater (P<0.05) in T2 (185.69±4.34); T1 (185.54±4.34) compared to T3 (166.97±4.34) which was lower. Treatments 1 (204.17±6.57), T2 (197±6.57) had heavier (P<0.05) breast weights than T3 (186.06±6.57). Dietary treatments had no significant effect (P > 0.05) on pH of the breast meat. No differences were observed in colour during the 1 hour period after slaughter. At 24 hours after slaughter, the L* values were different (P < 0.05) in T1 and T2 (44.3 ± 0.37; 43.7 ± 0.37), respectively, T1 and T3 were the same. The a*-values were different (P < 0.05) at 48 hours after slaughter for T1 and T3 (4.5 ± 0.27; 3.4 ± 0.27), T2 was the same as T1. It was therefore, concluded that since manipulation of starter phase did not have adverse effects on growth performance, gross profit, slight statistical difference in meat quality attributes and carcass characteristics. Therefore, the manipulation of starter diet has the potential to be used in broiler production.

Calcium status is a major factor in the regulation of reproductive activity in the hen. Restriction of dietary calcium (Ca) or vitamin D (D) is assumed to cause cessation of ovulation through decreased plasma calcium concentrations. Several studies suggest that there may be a threshold level of ionized calcium (Cai) below which ovulation will not proceed. The objectives of this thesis were to determine how Cai concentration is involved in the process of ovulation by comparing Ca and D-deficient hens, that had ceased laying, with control birds that were laying normally. A secondary objective was to determine the effects of multiple blood sampling (MBS) on the hen's ovulatory cycle. SCWL hens were divided into three groups-control, Ca-deficient and D-deficient groups and fed respective diets. Control birds were serially sampled every two hrs for 24-26 hrs immediately after oviposition until the next oviposition. Deficient birds, that had ceased laying for 10 to 14 days, were sampled at the same time. MBS was achieved with an indwelling vascular access port. Six birds/experimental group were used. Control birds were bled two weeks later from late afternoon until the following day at the same time. Whole blood was analyzed for Cai. Separated plasma was analyzed for total calcium (Cat), inorganic phosphorus (Pi), estrogen (E₂), progesterone (P₄) and l,25(OH)₂D₃ concentrations. Tibiae were ashed for mineral content. In expt. 1, the effect of MBS on the ovulatory pattern of hormones and ions was observed by sampling control birds twice, using two different time courses. Patterns and concentrations of the hormones and ions, regardless of time course, were similar to previous studies. Overall treatment effects were only significant between treatments with regards to total calcium and estradiol concentrations. The large loss of plasma proteins during the bleeding regime resulted in a steady decline in Cat over the 26 hrs, however, it was still within the physiological range of laying birds. . E₂ concentrations were also affected due to interruption of the laying sequence. However, this can be avoided since some birds continued to lay. In expt. 2, the control group had significantly higher mean plasma Cat and Pi concentrations and bone ash than both the deficient groups. Control and D-deficient groups had similar mean Cai concentrations, however, the ovulatory profile of the control group had a significant cyclic pattern over the 24-26 hrs, whereas, both deficient groups did not vary significantly over the 24 hrs. Plasma Pi concentration in the control group, not previously described, was cyclic in nature, related to the egg laying cycle. Plasma l,25(OH)₂D₃ concentrations were significantly higher in the Ca-deficient group than the control group. D-deficient birds had detectable levels of plasma 1,25(OH)₂D₃, but it was significantly lower than the control group. Plasma E₂ and P₄ concentrations were significantly higher in the control group In conclusion, it would appear that an inter-relationship exists among Cai, Pi and 1,25(0H)₂D₃ and the reproductive hormones. A threshold concentration of Cai may be the trigger for ovulation, perceived at the level of the pituitary, hypothalamus or ovary. A threshold of Pi and a window of l,25(OH)₂D₃ concentration may also have permissive roles in ovulation. In addition, MBS, regardless of time course, can be used as a method for determining ovulatory profiles in individual birds without seriously affecting ionic and hormonal concentrations and patterns. / Land and Food Systems, Faculty of / Graduate

Availability of six minerals (Ca, P, Mg, Mn, Zn, and Cu) in commercial wheat, triticale, corn and barley samples was estimated with three-week old growing chicks. Effects of soybean meal and wheat fed at different dietary concentration on availability of these minerals were studied. The availability of minerals from specific inorganic sources were also evaluated. Availability value was determined by a balance procedure corrected for endogenous minerals. Results indicated that the availability of calcium, phosphorus, magnesium, manganese, zinc, and copper was 71.0, 67.4, 53.5, 48.4, 49.6 and 78.5%, respectively for the wheat and triticale samples. Copper availability was the highest in corn (87.2%), followed by calcium (70.0%), phosphorus (60.9%), manganese (60.0%), zinc (57.5%) and magnesium (51.0%). The availability of Ca, P, Mg, Mn, Zn and Cu in barley was 68.9, 68.8, 54.9, 54.9, 49.1 and 77.5%, respectively. Significant variation (P ≤ 0.05) exists among the cereal grains tested. Results indicate that mineral availability is influenced by the origin of the samples obtained. Availability of minerals is affected by the concentration of ingredients in the test diet. Significant differences (P ≤ 0.05) were observed in availability for all the minerals tested when soybean meal and wheat were supplied in the test mixture at five levels. Calcium and phosphorus from calcium phosphate were highly available to growing chicks. However, the availability decreased rapidly when the mineral level was in excess of the dietary requirement. Six levels of magnesium (150, 300, 450, 600, 750, and 900 ppm) from magnesium carbonate were evaluated. Results showed that magnesium was highly available to growing chicks. The values ranged from 82.3 to 61.9%. Excess amounts of magnesium in the diet tended to reduce the availability value. Various levels (25, 50, 75, 100 and 125 ppm) of manganese from manganese sulfate were tested. Manganese appeared to be poorly available for the levels tested. Zinc availability from zinc oxide was highly available for the chick. The availability values/ranged from 84.4 to 93% for all the diets containing 25 to 125 ppm of zinc. The availability of copper from copper sulfate was moderate to high (72.1-80.2%) for the low dietary copper concentrations (2-32 ppm). However, the copper availability values (61.8-63.6%) tended to decrease at higher dietary concentration (50-250 ppm). / Land and Food Systems, Faculty of / Graduate

Methane (CH₄) production from enteric fermentation in ruminant animals is a contributor to global greenhouse gas emissions. Because CH₄ has an impact on increasing global temperatures, there is a push for government regulations to reduce CH₄ from livestock animals. At 1.9% of U.S. CH₄ emissions beef cattle are a large contributor to agricultural CH₄ emissions or (EPA, 2020). Enteric CH₄ emissions are also a loss of energy for the animal, accounting for 2-12% of energy loss from the ruminant animal (Johnson & Johnson, 1995). This energy loss from the diet is contingent upon forage content, where increasing forages in the diet increases CH₄ yield (g/kg of gross energy intake; van Gastelen et al., 2019). Mootral is a feed supplement that contains garlic (<i>Allium sativum</i>) and bitter orange (<i>Citrus aurantium</i>) extracts. The organosulfur compounds in garlic the flavonoids found in bitter orange extracts are known to decrease CH₄ production, (Busquet et al., 2005a; Balcells et al., 2012; Seradj et al., 2014). However, it is unclear how the forage content and Mootral inclusion will interact to effect CH₄production and animal performance. Because feedlot cattle are fed a range of forage:concentrate ratios while in the feedlot, it is important to know how effective mitigation strategies are in different forage:concentrate diets. Therefore, the objective of the current study was to quantify CH₄ production and determine growth, intake, and carcass characteristics of feedlot steers fed Mootral in diets with a low, medium, and high forage content. Knowing the effect of garlic and flavonoids on methanogenesis, we hypothesized that Mootral would decrease CH₄ emissions without impacting growth, intake, and carcass characteristics of feedlot steers. We expect that the CH₄ mitigating ability of Mootral will be greatest in the diet with the most forage. For the experiment, 144 Angus x Simmental steers were allotted by body weight (BW; 363 kg, breed composition, and farm origin to a 3 x 2 factorial arrangement of 6 treatments (4 pens per treatment) to determine the effect of Mootral (garlic + citrus extract; 0.25% of the diet DM vs. 0.0%) on methane emissions, growth and carcass characteristics of feedlot cattle. During the first 84 days, cattle were fed three different forage concentrations in the diet (15, 41.5, or 68% corn silage) with or without Mootral. From day 85 to slaughter, corn silage was included at 15% of the diet DM with or without Mootral. Methane emissions were measured on day 42-46 and day 203-207. Data were analyzed using the GLIMMIX procedure of SAS. There was an interaction (<i>P </i>= 0.03) between forage content and Mootral for DMI from d 0 to 84, where Mootral decreased DMI of steers fed 15% corn silage but did not affect DMI of steers fed 41.5 or 68% corn silage. There were no effects (<i>P </i>≥ 0.22) of forage content or Mootral on BW or average daily gain at any time, or on DMI from d 84 to slaughter and overall. Intake from d 0-84 was lower and gain:feed from d 0-84 and overall was greater (<i>P </i>= 0.04) for steers fed 68% compared to 15 or 41.5% corn silage. On d 42-46, steers fed 41.5 and 68% corn silage had increased (<i>P </i>≤ 0.02) methane emissions compared to steers fed 15% corn silage. Mootral did not affect methane emissions on day 42-46 (<i>P</i> ≥ 0.47), but there was a forage effect, where steers fed the 41.5 and 68% corn silage diets emitted more methane on a g/d (<i>P</i> = 0.05) and a g/kg of DMI (<i>P</i> = 0.007) basis and tended (<i>P</i> = 0.07) to produce more methane on g/kg BW basis compared to steers fed the 15% corn silage diet. Steers fed Mootral emitted less (<i>P </i>≤ 0.03) methane on a g/d, g/kg DMI, and g/kg BW basis on d 203-207 compared to steers not fed Mootral. Mootral tended to decrease (<i>P </i>≤ 0.09) fat thickness and yield grade. In conclusion, increasing forage content increased methane emissions and Mootral decreased methane production in 15% corn silage diets and improved carcass leanness.

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Digitized by Kansas State University Libraries

Digitized by Kansas State University Libraries

LD2668 .T4 1941 S62 / Master of Science

Call number: LD2668 .T4 1954 B7 / Master of Science