Cryopreservation of animal oocytes will permit germplasm of valuable or unique females to be preserved for extended times. The objective of this research was to derive a procedure to cryopreserve bovine oocytes by vitrification to be used as recipients for somatic cell nuclear transfer (SCNT). Caprine oocytes vitrified by the same procedure were assayed by cytological examination of microtubules. In the first two of three experiments, bovine oocytes matured in vitro were vitrified in a mixture of ethylene glycol (EG), dimethylsulfoxide (Me2SO) and trehalose, and then subjected to in vitro fertilization (IVF) or SCNT. For vitrification, oocytes were first exposed to increasing concentrations of EG + Me2SO, placed into the vitrification solution composed of 2.8 M Me2SO + 3.6 M EG + 0.65 M trehalose for 20 sec, immediately loaded onto 20-ìm cryoloops, and finally plunged directly into liquid nitrogen (LN2). Vitrified oocytes were warmed by direct immersion of cryoloops into 0.25 M trehalose prepared in TCM-199 medium at 37°C, rinsed briefly, and then assayed. In Experiment I, of 327 bovine oocytes subjected to IVF after being vitrified, 267 cleaved and 32 (9.8%) formed blastocysts, compared to 32.1% blastocysts for control oocytes. In Experiment II, of 266 bovine oocytes enucleated after vitrification and subjected to SCNT, 248 formed couplets, 152 of which cleaved and 31 (12.5%) developed into blastocysts, compared to 33.0% blastocysts for controls. During the course of Experiment II, 20 of 31 blastocysts derived by SCNT of somatic cells from a Brahman cow into vitrified oocytes were transferred into recipients, resulting in three pregnancies and the birth of one Braham calf that has survived to adulthood. In Experiment III, cytological analysis of caprine oocytes vitrified by the same procedure used for bovine oocytes demonstrated that their microtubules were normal, suggesting that this same procedure can also be used for the former species. The results demonstrate that bovine oocytes can be successfully vitrified and warmed, yielding normal embryos after fertilization or SCNT. Additional research is needed to verify that caprine oocytes vitrified by this method can also develop into kids.

The purpose of this research was to determine requirements for amino acids that limit the use of crystalline amino acids, to determine the effects of reducing crude protein, and to evaluate the problems associated with low crude protein diets for swine and poultry. Four experiments were conducted to determine the Lys and sulfur amino acid requirements for 5- to 10-kg pigs. The results of these experiments suggest pigs in this weight range require a diet containing 1.40% true digestible (TD) Lys and the ratio of sulfur amino acids to Lys is not greater than 0.54. Two experiments were conducted to determine the requirement of Lys and sulfur amino acids in 90-kg barrows using plasma urea nitrogen as the response. These experiments indicate a TD Lys requirement of 0.57% and there was no response to TD sulfur amino acid concentrations above 0.27%. Six experiments were conducted to evaluate the Ile requirement of 80- to 120-kg barrows. These experiments indicate a requirement of 0.34% TD Ile in a corn-blood cell diet; however, the requirement may not be greater than 0.24% in barrows fed a corn-soybean meal diet. Two experiments were conducted to evaluate the effects of soybean meal and lowering crude protein in diets for late-finishing barrows. Results suggest that reductions in soybean meal are not the cause of increased carcass fat in pigs fed low crude protein diets. Furthermore, the fortification of a corn diet with crystalline Lys, Trp, and Thr will not support optimal growth or carcass composition. Five experiments were conducted to determine the effects of lowering crude protein in diets for broilers and to evaluate limiting essential and nonessential amino acids. Results indicate that low crude protein diets can support optimal growth of broilers when surfeit Gly is supplied in the diet. The requirement of Gly + Ser appears to be not less than 2.14% from d 0 to 17 posthatching.

The influence of donor animal sex or age on in vitro bovine cell culture was evaluated to provide foundation information for the selection of donor tissue for nuclear transfer. Skin biopsies were taken from each of sixteen individuals including four bulls (B), four cows (C), four male calves (MC), four female calves (FC). At passage 2, cells from in vitro culture of cell lines were influenced not by gender but by age in the mean cell generation time (MGT). When evaluating familial lineage, comparison between related and unrelated groups showed that most comparisons do not show significant differences in lag time, stationary phase viable cell counts (SPCC) and MGT. In each cell line, there was high cell viability throughout the growth curves, indicating stable cell maintenance and proper cell harvest was conducted in this study. At passage 4, MGT of each cell line was not influenced by age but by sex at passage 2, however, at a later cell passage (by passage 4), the MGT of each cell line was not affected by either sex or age of the donor. By passage 4, the MGT of each cell line was not affected by either sex or age. As passages continued, the extrinsic environmental factors likely influenced the MGT. Cell cycle analysis at passage 4 on day 0 of this study showed that > 90% of cells were in G0/G1 portion in each cell line of all groups. Cell lines from younger donors were more frequently at higher G0/G1 percentages, or synchronized than those derived from older donors. Thus, age of donor animal could be a factor in selecting cell line for NT, especially when G0/G1 nuclei are intended for use. Male groups (B and MC) showed higher stationary phase viable cell counts than female groups (C and FC). Most comparisons showed no significant differences in lag time, SPCC and MGT between related and unrelated familial lineage groups. Each cell line showed constant viability (94.36 to 97.98%) at passage 4 throughout the growth curves.

Paternal half-sib groups of Brahman bull calves were purchased at weaning from purebred Brahman producers in Louisiana. Following backgrounding and grazing on ryegrass the steers shipped to a commercial feedlot in south Texas. Steers were slaughtered in groups when they reached an approximate average endpoint weight of 535 kg and 10mm backfat. After a 24 hr chill, carcasses were ribbed, data collected, and a longissimus muscle sample taken for calpastatin assay. Two 2.54 cm thick steaks were randomly removed from the large end of the strip loin, vacuum packaged, and randomly selected for 7 and 14 days of aging. Genetic correlations and heritabilities were calculated with an animal model using MTDFREML. The means were 1.49 kg/d for ADG, 336.4kg for USDA yield grade, 58.7 cm2 for ribeye area, 0.87 cm for fat thickness, 2.12 for percent kph, 2.34 for USDA yield grade, and 390.3 for marbling score which equals a high select USDA quality grade. Other means were 10.60 and 10.59 for purge loss after 7 and 14 days aging, 21.07 and 21.56 for percent cooking loss, 4.57 and 3.85 kg for shear force after 7 and 14 days aging. Factors influencing shear force were marbling score, purge loss after 7 day aging, purge loss after 14 day aging, cook loss after 7 day aging, cook loss after 14 day aging, and calpastatin. Heritablilities for growth and carcass traits were similar to those of non-Brahman cattle. Heritabilities for cooking traits were low. Tenderness as affected by moisture loss during the thawing and cooking process needs to be studied further.

Two experiments were performed to discover what, if any, reproductive differences exist in high body condition (BCS) mares with varying concentrations of leptin. Previous research showed that mares with high body condition scores can have a range of leptin levels, from very low (<5 ng/mL) to very high (>10 ng/mL). Earlier results indicated that most mares with high body condition scores maintain estrous cycles or show significant follicular activity during the winter. Among these high BCS mares, about 30% of them exhibit hyperleptinemia and hyperinsulinemia. The first experiment was designed to compare the reproductive characteristics of high BCS mares with high versus low leptin levels during vernal transition and the first estrous cycle. Also, an IVGTT, insulin challenge, and two sulpiride challenges were performed to characterize endocrine profiles of these mares. Results of these challenges were similar to previous work, in that hyperleptinemic mares had greater insulin responses to glucose and greater clearance rates of infused glucose compared to low leptin mares. These mares also showed a slightly greater prolactin response to sulpiride than their low leptin counterparts. When analyzing the reproductive traits of these mares, no differences between groups existed for follicular sizes or distributions, gonadotropin levels, or date of first ovulation. The second experiment was designed to assess what differences may exist between high BCS mares with high versus low leptin levels with regard to their gonadotropin and ovarian responses to several analogs of gonadotropin releasing hormone (GnRH). Histrelin and deslorelin appeared to be the most potent of the analogs, followed by buserelin and then GnRH. Leptin status did not appear to affect the gonadotropin response or time to ovulation for any of the analogs used in this trial. In conclusion, although hyperleptinemic mares showed altered insulin and glucose characteristics, no significant reproductive differences were observed between these mares and their normal counterparts in terms of ovarian function or the hypothalamic- pituitary axis during vernal transition or the estrous cycle.

The low survival rates of nuclear transfer fetuses and neonates in goats and cattle have been linked to placental abnormalities. A series of studies was designed to investigate the possibility of supplementing nuclear transfer embryos with electrofused embryos to generate placental tissue in goats and cattle. The initial study was designed to determine if the breeding season of goats could be extended with hCG treatment. Progesterone concentrations in treated does increased but pregnancy rates were unaffected. In the second study, goat embryos were electrofused and combined with nuclear transfer embryos at the 8-cell stage to produce the first offspring as a result of electrofused embryo complementation in goats. The remainder of the studies focused on electrofused embryos in cattle. The method of electrofusion was studied and it was determined that fusion efficiency and developmental rates after two fusogenic pulses were not different from fusion efficiency and developmental rates after a single pulse. The latter study also showed that the time of cleavage following in vitro fertilization affected the cleavage and blastocyst rates of embryos after electrofusion. In the next study, electrofused embryos were aggregated with nuclear transfer embryos at the 8-cell stage. Aggregate embryos developed to the blastocyst stage at the same rate as electrofused and nuclear transfer control embryos. The final study was a series of experiments conducted to characterize the nuclear status of electrofused embryos. In the first and second experiments of the series, embryos were stained following electrofusion and it was found that more embryos were tetraploid and fewer were binucleate when embryos were electrofused later after cleavage. The third and fourth experiments in this series examined the stage of the cell cycle prior to electrofusion. These experiments indicated that the embryos electrofused at 30 hours post-insemination were in the G2 phase of the cell cycle. It was concluded that the stage of the cell cycle would be an important factor in the production of tetraploid embryos via electrofusion and this should be the basis of future research in this area.

This research was conducted to determine the effects of feeding different P levels with and without phytase supplementation on broiler growth performance, bone breaking strength (BBS), and P excretion. An experiment with 4 trials was conducted with 7,840 Ross x Ross straight run broilers. For each trial, 1,960 broilers were allotted on d 0 to 4 treatments with 7 replications per treatment with 70 broilers per replication. The broilers were fed a 4 period feeding program consisting of starter (0 to 14 d), grower (14 to 32 d), finisher (32 to 41 d), and withdrawal (41 to 50 d) periods. For each trial, the same pen was used continuously for each treatment/replication combination, and the litter was not removed between trials. Broilers were fed a control diet (0.43, 0.40, 0.36, or 0.32% nonphytate P (nPP) in the starter, grower, finisher, and withdrawal periods, respectively), a low Ca and P (LCaP) diet with a 0.05% reduction in nPP in each period, and these two diets supplemented with 600 phytase units/kg (nPP was reduced by 0.094% in diets with phytase). Diet did not affect (P > 0.10) broiler performance in the starter or withdrawal periods. Generally, both phytase addition and the LCaP diet decreased some aspects of growth performance during the grower and finisher periods. There was no main effect of phytase on BBS, but BBS was decreased in the broilers fed the LCaP diet with phytase addition (nPP x Phy, P < 0.01) in the grower period, and BBS was decreased in finisher (P < 0.02) and withdrawal (P < 0.01) periods for broilers fed the LCaP diet. Total P (TP), soluble P (SP), and reactive soluble P (RSP) were decreased (P < 0.04) in the litter of broilers fed the LCaP diets. Total P was decreased (P < 0.01) in the litter of broilers fed phytase, but SP and RSP were not affected (P > 0.10) by phytase. These data indicate that phytase supplementation at 600 phytase units/kg reduces growth in some periods, has no effect on BBS, and that phytase reduces TP but not SP or RSP in the litter.

Rapid growth of warm-season grasses such as bermudagrass (Cynodon dactylon) and bahiagrass (Paspalum notatum) is associated with a decline in their nutritional value. This study was initiated to provide production and composition data with different cultivars of bermudagrass (common, Russell, Jiggs) and bahiagrass (Tifton-9, Pensacola, Argentina). Dry matter (DM), ash, crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) composition and production were evaluated every two weeks for a ten-week period on six different cultivars. Also, Russell bermudagrass was evaluated in a second trial very similar to the first trial for composition and production but was started at three different harvest times. Bermudagrass cultivars had higher DM (P < 0.05) than bahiagrass at all stages of maturity except for d 14. Dry matter production was less than 2000 kg/ha at the 14-d harvest for all of the cultivars. Jiggs produced more DM (P < 0.05) than the other grasses at 42-d harvest. Ash (%) decreased at a constant rate from day 14 until day 70. There was no significant difference (P > 0.05) among the three bermudagrasses and Argentina bahiagrass CP (%) at the 14-d harvest. Russell produced the least amount (P < 0.05) of CP at d 14, while Argentina produced the most CP. Russell, common, and Pensacola CP production (kg/ha) were similar (P > 0.05) and each were higher than Tifton-9 and Argentina after 42 days of growth. Bahiagrass NDF (%) was similar (P > 0.05) across the three cultivars at each of the different harvest times except for the 42-day harvest where Argentina had higher NDF levels (P < 0.05) than either Tifton-9 or Pensacola. The bahiagrass cultivars were similar (P > 0.05) in NDF production at 42 days. Jiggs produced more (P < 0.05) NDF than the other grasses at 56 and 70-d of growth. Common had the least amount of ADF at 56 and 70-d harvest (P < 0.05). ADF production was the highest (P < 0.05) in Jiggs from d 28 to d 70 of growth. Russell early- and mid-season harvest had greater (P < 0.05) DM (%) and production than in the late season. Crude protein was the highest (P < 0.05) in both the early and mid season harvested Russell. The late season harvested Russell produced the least amount (P < 0.05) of DM and the least amount (P < 0.05) of CP. It was predicted that the late season harvested Russell would maintain DM and CP production at a constant rate for a longer period of time. This means that it would allow a producer a wider range of time to make hay or even graze this forage at that time of the year.

Eighty-six primiparous or multiparous sows and their pigs were used to evaluate the effects of changing dietary cation-anion difference (DCAD) in late gestation and in lactation on sow productivity. Twenty sows were used in Exp. 1, and the dietary treatments consisted of a positive control (PC) corn-soybean meal (C-SBM) diet with four levels of DCAD (140, 99, 75, and 45 mEq/kg). These DCAD’s were achieved by four levels of SoyChlor (SC) additive (0, 1.5, 2.5, and 3.5%). In Exp. 2, 66 sows were used and the dietary treatments consisted of the diets providing DCAD of 140 and 45 mEq/kg. The diets were fed from d 107 of gestation to weaning in Exp. 1 and from d 111 of gestation to weaning in Exp. 2. Sows were allotted based on parity and their farrowing date. Experiment 1 was a preliminary experiment to determine the level of DCAD that reduced urinary pH. Reducing DCAD did not affect sow reproductive responses. Urinary pH was linearly decreased (P < 0.001) as DCAD decreased in the diet. Reducing DCAD tended to linearly increase (P = 0.15) plasma Ca concentrations. In Exp. 2, reducing DCAD from 140 to 45 mEq/kg reduced ADFI from d 111 of gestation to d 1 postfarrowing (P < 0.02), but ADFI was not affected by DCAD during any other period. Reducing DCAD did not affect reproductive performance of the sows nor litter response variables or plasma Ca. Decreasing DCAD in the diet decreased urinary pH (P < 0.001). Twenty-seven sows fed the PC diet and 21 sows fed the reduced DCAD diet during the previous lactation were evaluated during their subsequent farrowing. Sows that were fed the reduced DCAD diet had increased total number of pigs born (P < 0.08) and pigs born alive (P < 0.02) in the subsequent farrowing. Changing DCAD had little affect on sow and litter response variables in the current lactation, but it decreased urine pH (P < 0.001), and increased total number of pigs born (P < 0.08) and pigs born alive (P < 0.02) in the subsequent farrowing.

Three experiments were conducted to determine the effects of the chromium propionate (CrProp) in swine and poultry diets. Two broiler experiments, each utilizing 1,460 Ross X Ross broilers, were conducted to evaluate the effects of 0, 200, 400, or 800 ppb CrProp on growth performance and carcass traits in 0 to 42 and 0 to 49 d-old broilers. In Exp. 1, 400 ppb Cr decreased (P < 0.10) ADG and G:F in the grower phase, but mortality was reduced (P < 0.10) in broilers fed 200 ppb or 800 ppb Cr. In the finisher phase, G:F was increased (P < 0.10) in broilers fed all dietary levels of Cr, and mortality was reduced (P < 0.10) in broilers fed 200 and 400 ppb Cr. Chromium did not affect the overall growth data or carcass traits. In Exp. 2, CrProp did not affect growth performance. The results indicated that Cr as CrProp improved G:F in the later phases of growth and reduced mortality in Exp. 1 but not in Exp. 2. In Exp. 3, 108 crossbred Yorkshire gilts were used to examine the effects of 0 or 200 ppb CrProp on iodine value, fatty acid profile of fat, growth, carcass traits, and pork quality from gilts fed tallow or choice white grease (CWG). Chromium decreased (P < 0.03) 10th rib back fat and increased (P < 0.02) percent muscle. Gain:feed was increased (P < 0.003) and ADFI decreased by fat addition. Fat increased hot carcass weight (P < 0.07) and dressing percent (P < 0.02). Average back fat, 9th rib CL, and total loss were decreased (P = 0.02 to 0.04) by tallow. Belly width was increased (P < 0.08) by tallow, but belly bending on both the teatline and scribe side were increased (P = 0.004 to 0.01) by CWG. Iodine values on belly and loin samples were increased (P < 0.001) by CWG. Overall, Cr affected BF and percent muscle and the inclusion of tallow decreased (P = 0.03 to 0.09) belly and loin iodine value further than CWG or no added fat.