Thesis (MSc. (Animal Production)) -- University of Limpopo, 2016 / A study was conducted to determine the effect of shredded Colophospermum (C.) mopane wood inclusion as roughage on performance of fattening Nguni heifers weighing 200 ± 5kg. The four diets used were isocaloric and isonitrogenous but with different shredded C. mopane wood inclusion levels of 5 (F95M5), 8.5 (F91.5M8.5), 10 (F90M10) and 15 (F85M15) %. The heifers were randomly allocated to the treatments in a completely randomized design. A quadratic equation was used to determine the shredded C. mopane inclusion levels for optimal productivity of the heifers. Shredded C. mopane wood inclusion level had effect (P<0.05) on intake and feed conversion ratio (FCR). Diet DM, OM, CP, NDF and ADF intakes per metabolic weight and FCR of Nguni heifers were optimized at different shredded C. mopane wood inclusion levels of 11.0, 13.7, 8.0, 15.0, 14.0, 14.0 and 15%, respectively. However, shredded C. mopane wood inclusion level did not affect (P>0.05) diet in vitro digestibility, carcass weight, dressing percentage, meat pH, meat shear force values and meat colour intensities except for red colour intensity of rump steak. It was, thus, concluded that shredded C. mopane wood can be used as roughage without adversely affecting diet intake, FCR, and live weight of Nguni heifers. However, diet intake and FCR were optimized at different C. mopane wood inclusion levels.

In this study 272 beef heifers were studied from just prior to their first breeding season (15 October 2003), through their second breeding season and until just after they had weaned their first calves in March 2005. The study consisted of two main parts: in the first part, heifers were randomly allocated to either a synchronised TEST group or an unsynchronised CONTROL group. The TEST group received artificial insemination (AI) for 6 days followed by prostaglandin F2á (PGF) treatment on day 6 (PGF/6) and further AI for a total of 50 days, which was followed after a 6 day break by a 42 day bull breeding season. The CONTROL group were bred for the same period without PGF treatment. Synchronisation resulted in a reduction in days to first insemination (P < 0.01) and days to calving (P = 0.04). No significant difference could be demonstrated in pregnancy rate to the 50 day AI season (60.0% vs. 51.8%, TEST and CONTROL groups respectively, P = 0.18), final pregnancy rate (82.2% vs. 83.2%, P = 0.87) or pregnancy rate to the subsequent breeding season (96.0% vs. 95.0%, P = 1.00). A significant increase in mean weaning mass of the calves due to synchronisation could not be demonstrated (207.0 kg vs. 201.4 kg, TEST and CONTROL groups respectively, P = 0.32). However, data from this study were used to calculate the benefit:cost ratio, and a value of 2.8 was reached, representing the return on investment for the synchronisation protocol under these circumstances. It was concluded from this study that a PGF/6 protocol may lead to a change in the total mass of calves weaned by changing days to calving and thus weaning mass, birth mass of calves, weaning rate and/or the ratio of male:female calves born. It was further concluded that a practical way to predict the cost effectiveness of an oestrus synchronisation protocol is to determine the ratio between the total cost of the programme and the price of weaner calves per kg live mass. This ratio represents the minimum increase in mean weaning mass that has to be achieved for the programme to be cost effective if no increase in weaning rate is achieved. In the second part of this study, reproductive tract scoring (RTS) was performed on the same group of heifers one day before the onset of their first breeding season. The effect of RTS on several reproduction and production outcomes was tested, and the association of RTS with the outcomes was compared to the associations of other input variables such as mass, age, body condition score (BCS) and Kleiber ratio using multiple or univariable linear or logistic regression. RTS was associated with pregnancy rate to the 50 day AI season (P < 0.01), days to calving (r = 0.28, P < 0.01), calf weaning mass (r = 0.22, P < 0.01) and pregnancy rate to the subsequent breeding season (P < 0.01). These associations were mostly independent of associations with mass, age and BCS before the onset of the first breeding season. RTS was a better predictor of fertility than was Kleiber ratio, and similar in its prediction of calf weaning mass. It was concluded from this study that RTS is a unique predictor of heifer fertility, compares well with (but is independent of) other traits used as a predictor of production outcomes and is likely to be a good predictor of life production of the cow. / Dissertation (MSc (Veterinary Sciences))--University of Pretoria, 2006. / Production Animal Studies / unrestricted

Während der Kalbung kommt es neben physischen Belastungen auch zu weit reichenden Veränderungen auf hämatologischer und klinischchemischer Ebene. Durch verschiedene Prozesse kommt es zusätzlich zur Entstehung von oxidativem Stress. Zusammen hat dies einen entscheidenden Einfluss auf das Wohlbefinden, die Gesundheit und die Leistung der Kühe im postpartalen Zeitraum. Ziel der vorliegenden Untersuchung war es, die antioxidative Kapazität und den Stoffwechsel von Färsen im geburtsnahen Zeitraum unter Berücksichtigung des Geburtsverlaufes und des Gesundheitsstatus post partum zu analysieren.

Forage intake by animals is an important factor in determining production of livestock products from rangelands. However, relatively little is known of effects of such forage variables as availability and distribution in space upon intake. Even less is known about how the grazing animal modifies its feeding tactics when confronted with diminishing or limited supplies of available forage and how such altered behavior may affect the animal's energetic cost for existence. Forage intake, body weight gain, grazing time and biting rate of Angus heifers was related to forage availability and plant height on semiarid crested wheatgrass rangeland during the late summer. Forage availability was estimated within 10 percent of the 2 mean (P2plots. Forage intake was estimated from data on fecal production and in vitro digestibility of forage. Fecal production was determined by total collection, using fecal collection bags, and by a single-dose marker technique, used to estimate fecal production indirectly. Digestibility was determined by an in vitro procedure. Additionally crude protein and cell contents of forage were determined. Grazing time was measured by mechanical grazing clocks (Vibracorders) mounted on animals' necks. Biting rate was determined visually using a stop watch to time specific grazing intervals during which all bites were counted. There were a total of four 4-day trials during 1977 and five 4-day trials during 1978. Crude protein content within years was significantly higher during the third period in 1977 and during the fifth period in 1978 when regrowth occurred. Within years, in vitro digestibility was significantly higher only for the fifth trial during 1978. Cell contents decreased as grazing progressed only during 1978. Crude protein content, cell contents and in vitro digestibility were higher during 1977 than 1978. Forage intake of heifers did not vary significantly among successive grazing trials as forage availability declined from 919 to 143 kg DM/ha. Heifers apparently compensated for the diminishing forage availability by increasing grazing time from 380 to 656 min/day and biting rate from 37 to 50 bites/min. Grazing time was inversely related to forage availability and was expressed by the relationship y = 676.8 - 0.3x; r2 = 0.93. Biting rate was less correlated with forage availability and was described as y = 50.4 - 0.02x; r2 = 0.86. However, biting rate was more closely correlated with plant height as described by the relationship y = 53.0 - 0.48x; r2 = 0.95. Heifers maintained or gained 0.1 to 0.7 kg/head/day weight during all trials except the last trial in 1978 when they lost approximately 1.1 kg/head/day. The weight loss for this trial was apparently not a result of restricted forage intake or limited forage quality but partly due to extra maintenance energy expenditures attributable to increased grazing time and biting rate. Correlation between estimates of fecal output by the single dose marker technique with total fecal collection were not significant (P

Heifers should represent the greatest genetic potential within a dairy herd. To maximize this potential, heifers must be inseminated to proven sires, a practice requiring management changes on many dairies. Holstein heifers (n=115) were allotted to one of three groups to compare alternatives to daily estrous detection that may facilitate the management of a program of artificial insemination for heifers. Group 1 heifers (Controls) received no treatment but were observed twice daily for signs of estrus. Group 2 heifers (2X-PGF) were synchronized with two injections of prostaglandin F2 alpha given 11 days apart and observed for estrus. Group 3 heifers (MGA+PGF) were synchronized with 9 days of melengestrol acetate feeding and an injection of prostaglandin F2 alpha 14 days after the last feeding and observed for estrus. Comparisons were made on the effectiveness of each treatment in estrous response and pregnancy rates and on the management requirements and economics associated with each program. Estrous response was significantly higher for the 2X-PGF group, while synchronized pregnancy and first-service conception rates did not differ. On an annual basis, the MGA+PGF group was calculated to require three-quarters of the labor input as compared to the 2X-PGF group and less than a fifth of the labor required for the Control group. A program of daily estrous detection was calculated to have an economic advantage over synchronization the frequency estrous synchronization programs was scheduled four times per year. was increased to six times per when When year, synchronization had a slight economic advantage over daily estrous detection when animal numbers were low and labor costs were high. The economic advantage of daily estrous detection is reduced when synchronization is performed more frequently throughout the year.

Causative factors and some consequences of dystocia were examined in 3923 parturitions among Hereford and Angus x Hereford crossbred two-year-old heifers. Fifty percent of the parturitions required some assistance. Minor assistance was required in 34.5% of the parturitions and major assistance involving use of a calf puller, in 15.1%. Caesarean section and foetotomy were rendered in 0.3% and .05% of the cases, respectively. Abnormal presentation at birth, which included leg back, head back, backwards, hiplock and breech, was observed in only 2.9% of the births and therefore is a minor contributor to dystocia. The major causes of dystocia were not specifically identified in this study. Sex of calf had a definite influence upon the degree of calving difficulty with male calves requiring more assistance in both minor and major assistance categories. Crossbred heifers had a higher percentage of unassisted births (62.4% vs 36.7%) than Hereford heifers. Ninety and eight-tenths percent of all calves born were alive at 30 days postpartum. Of the 9.2% that died, 6.2% died at birth or within 24 hours after birth. Losses were particularly heavy in this early period among those to whom major assistance had been given, with 71.5% of all deaths in this group being in this early period. Death loss rate was higher in this group throughout the 30 day postpartum interval with a total death loss of 38.6% as compared to a loss of 3.8% and 3.4% for the minor assisted and the unassisted groups, respectively. Among the kinds of abnormal presentations, death loss was greatest among breech presentations with a 66.7% loss. Backward presentation ranked next followed, in order, by head back, hiplock and leg back. Loss from leg back, 21% was relatively low. Increases in degree of severity of dystocia was accompanied by increases in time required to complete the birth process. Labor duration and sex of calf were correlated with male calves requiring a longer parturition than female calves, 104 minutes vs 88 minutes, respectively.

Sixteen pregnant heifers (8 per group) were fed diets containing soybean meal or whole raw soybeans (WSB) to evaluate effects of the supplemental dietary fat provided by WSB during the last trimester of gestation (90 d) on performance in the first 5 wk of the subsequent lactation, during which both groups were fed the same diet. Despite similar DMI by both groups, heifers fed WSB had greater ether extract (EE) intake and tended to weigh more after calving. By 35 DIM, heifers previously fed WSB had greater milk yield with a tendency for greater milk fat yield, although DMI was similar for both groups. Blood obtained by jugular venipuncture four times per day during gestation (-90 d, -69 d, -48 d, and -27 d), on day of calving (0 d), and during lactation (+35 d) was used to evaluate glucose and NEFA response to diet. Glucose concentration in blood plasma at -69 d and 0 d was lower in heifers fed WSB; whereas, plasma NEFA concentration was greater at -69 d, -48 d, and +35 d, but lower at 0d. Basal concentrations of glucose and NEFA in plasma and their response to insulin challenge (.26 IU per kg BW) were similar for both dietary groups at -30 d and +35 d. Plasma NEFA concentrations in response to insulin challenge, however, were greater at -30 d than at +35 d. Basal plasma triacylglycerol concentration was greater at -30 d and lower +35 d, due to feeding WSB during gestation. In addition, plasma 16:0 and 18:1 (%, wt per wt) concentrations were lower and 18:2 higher at -30 d in heifers fed WSB. At 35 DIM, heifers previously fed WSB again had lower 16:0 and higher 18:2 in plasma. Dietary treatment during gestation had no influence on long chain fatty acid concentrations in adipose tissue. Supplemental dietary fat provided by WSB for 90 d prior to parturition apparently altered the supply and metabolism of lipids in a manner that improved milk production during early lactation. / Master of Science

One hundred and eight Holstein dairy heifers were divided into two weight blocks based on beginning body weight (E = < 182 kg, light, > 270 kg, heavy). Heifers within weight blocks were randomly assigned to one of five treatments. Treatments consisted of three levels of NDF (35%, 45%, 55%) at 100% ofNRC TDN recommendation, and three levels of TDN (85%, 100%, 115 of NRC) at 45% NDF for light heifers. For heavy heifers, treatments consisted of three levels of NDF (40%, 50%, 60%) at 100% NRC TDN, and three treatments with similar levels of TDN at 50% NDF. Heifers were fed total mixed rations of corn silage, alfalfa haylage, ground orchardgrass hay, soybean meal, high moisture corn and a mineral mix formulated for 0.68 kg ADG. Mean gains (kg/d) were 1.07 and .96 for the light and heavy blocks, respectively. DMI as a percent of BWT differed across NDF levels for light heifers (3r'= 2.96, 2.56, 2.57, 2.57, and 2.87 % of BWT for the low, med., high NDF, and low, high TDN treatments, respectively). Heavy heifer DMI% did not differ (.Â¥= 2.45, 2.40, 2.24, 2.15, and 2.42 % ofBWT for low, med., and high NDF, and low, high TDN treatments, respectively). Equations to predict DMI were developed using intake information from this and a previous study. Backward stepwise regression was utilized to generate a simplified model. Model selected was: DMI (kg/d) = -5.9781 + (2.2120E-05 * BWTSQ) - (5.5527 * GAIN) + (2.7837 * GAINSQ) + (0.4668 * NDF) + (5.3930 * NDFSQ) + (0.03285 * DM) + 1 (7.7859E-03 * BWT * GAIN);11 = 514, rz = .67. / Master of Science

Optimization of reproductive efficiency of both beef and dairy herds is critical for sustainability and profitability. Two separate experiments were performed to test the reproductive outcomes following early weaning of beef heifers and intrafollicular insemination in dairy cows. Early weaning is a proven way to induce precocious puberty in heifers. Heifers will experience more estrous cycles before breeding, which is associated with increased fertility. In this experiment, heifers were either subjected to early weaning and a high concentrate diet (EW; 106.5±3.4 days of age) or normal weaning (NW; 231.7±3.33 days of age) treatments. Despite no effect (P>0.15) of weaning treatment on age at puberty, EW heifers tended to have higher pregnancy rates than NW heifers. A progesterone clearance analysis revealed that EW heifers also have greater ability to metabolize progesterone. This altered progesterone metabolism could be a direct result of changes in metabolism caused by feeding a high concentrate diet after early weaning. Pregnancy rates in cattle are often lower than desired. New reproductive advances are constantly developed to improve reproductive function. A recently described possible technique is intrafollicular insemination (IFI). The objective of the second experiment was to investigate whether IFI can cause fertilization. Abattoir ovaries with dominant follicles injected with semen and incubated overnight displayed sperm in close association with granulosa cells. When synchronized cows were subjected to IFI, no pregnancies resulted. While other studies have demonstrated success with IFI, it is still unknown if fertilization is possible within the follicle of the ovary. / Master of Science

At least five million heifers are raised annually in the United States to maintain the dairy cattle population and provide for our future needs. These animals are in reality the very foundation of the dairy business and the prosperity of everyone connected with it are dependent, at least to a certain extent, upon how well and how economically these animals are produced. Any practice that might possibly increase the efficiency with which these animals are raised is certainly worthy of thorough study and consideration. In the past the livestockman has paid little attention to the effect that frequency of feeding may have on the efficiency with which his animals convert feed to milk, meat, and. eggs. This is surprising when one considers the feeding behavior of the animal in its native or unconfined state. In its wild state the animal took in food throughout the day and also undoubtedly at night. The quantity eaten and the frequency of intake was entirely dependent upon the desire of the animal and the availability of feed. This condition still exists to a very large extent in the case of the free-grazing animal. However, with the closely confined or hand-fed animal both the quantity of feed eaten and the frequency of intake are regulated according to the judgment of the husbandman. Since this is a definite change from the feeding habits of the animal in its native state, it is conceivable that some change in the efficiency of feed utilization, if not the overall physiology, of the animal has occurred as a result of domestication. Like the livestockman the research worker has considered frequency of feeding to have little or no influence on his research results. A limited amount of work (15, 70, 27) has demonstrated that frequency of feeding is important in livestock production. If additional work confirms these results, it will become necessary to interpret past feeding experiments in the light of these new findings and to give more attention to frequency of feeding in future nutritional research. Such information would be of considerable practical importance since it would be a comparatively simple matter to design automatic feeders which would feed animals at periodic intervals. The present study was initiated to obtain data on the differences in body weight gain, digestion coefficients, heart rate, rectal temperature, rumination time, and rate of passage of food of dairy heifers fed equalized intakes of feed two and ten times daily. / Master of Science