A study was conducted to examine the impact of diet and cold weather on the excretion of nitrogen (N) and phosphorus (P) from beef cows, and the potential for these nutrients to be lost to waterways or as greenhouse gases (GHG). Feces and urine were collected from mature cows fed low-quality forage supplemented with DDGS to 0%, 10%, and 20% ww-1 in the fall of 2008 and winter of 2009. A detailed nutrient analysis was performed to determine forms of N and fractions of P in excreta. Feces, urine, and a simulated bedding pack were then applied to grassland to determine soil GHG emission. Cattle receiving DDGS supplementation excreted greater proportions of labile P in feces and greater concentrations of P in urine. The 20% DDGS diets had greater nitrous oxide emission from urine patches and greater proportions of available N in urine and feces.

Increased BCS at calving due to nutritional manipulation during the prepartum period resulted in greater mobilization of body fat after calving, regardless of plane of nutrition during the last 60 d of gestation. Although fatter cows were shown to have greater mobilization of reserves during the postpartum period, they maintained greater BCS at all points from calving to weaning compared to cows calving with fewer reserves at calving. A unique finding of this experiment was that the variation in BCS at calving was positively associated with BCS loss for cows fed to accrete BC during the prepartum period but was not associated with BCS loss for cows fed at maintenance levels during gestation. This finding suggests a threshold response in which BCS loss postpartum is only related to BCS at calving of 6.5 or greater. Progeny of fatter cows were heavier at d 40 and 84, but no treatment differences existed at weaning. The relationship between BCS at calving and calf BW at d 40 differed by treatment. This suggests a threshold response in which calf BW is positively related to increases in BCS up to 5.75. At BCS ≥ 5.75 calf weights were greater than at lower BCS levels but were unrelated to incremental changes in BCS. Altering dietary energy level during mid and late gestation altered the net lipolytic rate of beef cows and altered the timing of changes in tissue sensitivity and total lipolysis. Basal release of NEFA did not change for cows on a maintenance diet, but increased significantly for fatter cows prior to calving, whereas basal glycerol was unaffected by treatment. The stimulated release of glycerol was also unaffected by treatment, but increased across all periods. The ratio of stimulated glycerol and NEFA release to basal release of glycerol and NEFA indicate that the AT of HI cows has a delayed response to the increase in sensitivity to lipolytic stimulants that is associated with homeorhetic adaptations; however, at 7 d after calving, no differences were observed for net or total lipolytic capacity of the tissue. Providing mature beef cows ad libitum access to a high‐energy diet alters pre‐calving sensitivity of AT, but after calving and when animals are receiving a common diet, no differences in lipolysis were observed. Thus, BCS (4.91 to 6.56), as manipulated by diet, does not appear to impair lipolytic function and regulation in beef cows as observed in dairy cows.

A study was conducted to examine the impact of diet and cold weather on the excretion of nitrogen (N) and phosphorus (P) from beef cows, and the potential for these nutrients to be lost to waterways or as greenhouse gases (GHG). Feces and urine were collected from mature cows fed low-quality forage supplemented with DDGS to 0%, 10%, and 20% ww-1 in the fall of 2008 and winter of 2009. A detailed nutrient analysis was performed to determine forms of N and fractions of P in excreta. Feces, urine, and a simulated bedding pack were then applied to grassland to determine soil GHG emission. Cattle receiving DDGS supplementation excreted greater proportions of labile P in feces and greater concentrations of P in urine. The 20% DDGS diets had greater nitrous oxide emission from urine patches and greater proportions of available N in urine and feces.

Orientador: José Luiz Moraes Vasconcelos / Banca: Amauri Alcindo Alfieri / Banca: Marcos Bryan Heinemann / Resumo: O objetivo deste estudo foi determinar a incidência de perdas gestacionais em vacas de corte e avaliar o efeito da vacina contra IBR/BVD/Leptospirose (5,0 mL, Cattle Master® 4 + L5) na taxa de prenhez e perdas de gestação de vacas submetidas à Inseminação Artificial em Tempo Fixo [IATF, Protocolo; D0: benzoato de estradiol (2mg, Estrogin����) e inserção do dispositivo intravaginal de P4 (CIDR����, P4,1,9g); D7: dinoprost trometamina (PGF2α, 12,5mg, Lutalyse����); D9: retirada do dispositivo intravaginal de P4, administração cipionato de estradiol (0,5mg, ECP����) e remoção temporária de bezerros (RTB) por 48 horas; D11: IATF]. A avaliação de gestação foi realizada aos 30 e 120 dias pós IATF, para identificação de vacas prenhas e identificação de perdas gestacionais. No EXP1, foram avaliadas 8725 vacas para determinar a taxa de perda de gestação entre 30 e 120 dias. Foram usadas vacas pertencentes a dezenove propriedades com programas sanitários diferentes: sem imunização para doenças da reprodução (Grupo Sem, n = 7.311); com imunização semestral para Leptospirose (Grupo Leptospirose, n = 738); ou com imunização semestral para leptospirose e anual para Rinotraqueíte Infecciosa Bovina e Diarréia Viral Bovina (Grupo IBR/BVD/Leptospirose, n = 676). No EXP2 (n=1968) e EXP3 (n=2793), as vacas foram divididas aleatoriamente dentro do mesmo lote para receberem ou não a vacina contra IBR/BVD/Leptospirose (5,0 mL, Cattle Master®4 + L5): a primeira dose foi aplicada no início do protocolo de IATF e a segunda dose no momento do primeiro diagnóstico gestacional (US1/30d). No EXP2 as fazendas não utilizavam nenhum tipo de vacina preventiva para as doenças da reprodução, já no EXP3 as fazendas utilizavam vacinação contra Leptospirose. No EXP 4 foram utilizadas 367 vacas da raça Nelore... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to determine the incidence of pregnancy loss in beef cows, and evaluate the effect of the vaccine against IBR/BVD/Leptospirosis (5.0 mL, Cattle Master ® 4 + L5) in pregnancy rate and pregnancy loss of cows subjected to fixed-time artificial insemination [TAI, Protocol; D0: estradiol benzoate (2mg, Estrogin) and insertion of intravaginal P4 device (CIDR, P4, 1.9 g); D7: dinoprost tromethamine (PGF2, 5mg Lutalyse), D9: withdrawal of intravaginal P4 device, administration of estradiol cypionate (0.5 mg, ECP®) and temporary calf removal for 48 hours; D11: TAI]. The pregnancy diagnosis was performed at 30 and 120 days after TAI for identify cows pregnant and pregnancy loss respectively. In EXP1 8725 cows were evaluated to determine the rate of pregnancy loss between 30 and 120 days. The cows were from nineteen farms with different health programs. Cows without immunization reproductive diseases (Group No, n = 7311), with immunization semester to leptospirosis (Leptospirosis Group, n = 738) or semester immunization against leptospirosis and annual against infectious rhinotracheitis bovine and bovine viral diarrhea (Group IBR/BVD/Leptospirosis, n = 676). In EXP2 (n = 1968) and EXP3 (n = 2793) cows were randomly assigned within the same batch to receive or not vaccine against IBR/BVD/Leptospirosis (5.0 ml, 4 Cattle Master® L5 +): the first dose was administered at the beginning of the TAI protocol and the second dose at the time of first diagnosis of pregnancy (US1/30d). In EXP2 farms did not use any kind of preventive vaccine for diseases of reproduction, as in exp3 farms used vaccination against Leptospirosis. In EXP 4 367 nelore cows were submitted to TAI, the animals were randomly assigned to receive the vaccine at different times. Animals from groups:...(Complete abstract click electronic access below) / Mestre

Master of Science / Department of Animal Sciences and Industry / K C Olson / Prepartum fat supplementation has been associated with improved reproductive performance by cows managed for AI. Our objective was to evaluate the effects of prepartum supplementation with whole cottonseed or whole raw soybeans on response to ovulation synchronization and timed artificial insemination in mature beef cows. Cows (n = 188; average initial BW = 579 [plus or minus] 54 kg) were stratified by BCS and BW and assigned to 3 supplementation treatments: whole raw soybeans (21.6 % fat, 38.6% CP), whole fuzzy cottonseed (21.7% fat, 21.1% CP), or a 50:50 mixture of ground corn and soybean meal (2.6% fat, 30.6% CP). Supplements were fed at 1.8 kg per animal daily for 45 d before the first projected calving date (April 1). Supplementation was continued until each cow calved; thereafter, all cows received the control supplement until May 1. Ovulation was synchronized using the CoSynch + CIDR protocol and cows were bred via AI on June 21. Eleven d after AI, cows were exposed for natural service breeding for 50 d. Conception to AI was assessed 33 d after AI. Overall conception was assessed and conception to AI reaffirmed 126 d after AI. Body weight of cows fed control or oilseed supplements was similar (P > 0.3) at calving, initiation of ovulation synchronization, and at the end of the breeding season. Cottonseed-supplemented cows lost more BW and more BCS (P < 0.03) from the beginning of the trial to calving than those fed soybeans. Proportion of cycling cows was similar (P = 0.57) between treatments. Pregnancy to timed AI and final pregnancy rates were similar (P > 0.75) between control and oilseed-supplemented cows. Conversely, supplementation with cottonseed was associated with increased AI conception (P = 0.08; 54 and 39%, for cottonseed and soybeans, respectively) and greater final pregnancy rate compared to soybean-fed cows (P = 0.03; 100 and 93% for cottonseed and soybeans, respectively). Calf birth weights and calf weights at the end of the breeding season were similar (P > 0.24) between treatments. Effects of cottonseed and soybean supplementation on response to ovulation synchronization and timed AI by beef cows warrant further study.

In this experiment, the influence of phosphorus supplementation on growth and reproductive characteristics of beef cows in the semi-arid bushveld of South Africa was studied. The parameters in this study included weight, intercalving period and conception rates of cows, as well as birth weight, weaning weight and weight gain of calves. The experiment consisted of three trials. Trial 1 involved Bonsmara cows with four dietary supplementation groups. These were control, phosphorus supplementation all year round, phosphorus supplementation in the summer months and summer phosphorus supplementation with a winter lick. Trial 2 dealt with Bonsmara cows and included two dietary supplementation groups, namely control and phosphorus supplementation all year round. Trial 3 compared four different breeds (Afrikaner, Simmentaler, Nguni and Bonsmara) and included two dietary supplementation groups, notably a control group and a Kimtrafos 12 P supplementation all year round. Phosphorus supplementation had no significant effect on cow weight in Trial 1 (p > 0.1), but was significant in Trial 2 (p< 0.001) with the supplemented group performing better than the control group. In Trial 3, phosphorus supplementation had a varied effect on cow weight, because it only had an effect for the months of June to November (p< 0.05). Phosphorus supplementation had no significant effect on birth weight in any of the trials. Treatment did however either show a tendency towards significance or was significant for weaning weight and weight gain in Trial 2 (p= 0.0272 and p= 0.0524 respectively) and Trial 3 (p= 0.0587 and p= 0.0464 respectivey), with the treated groups performing better than the control groups. There was no improvement in calving interval or conception rate for phosphorus supplemented cows in any of the trials. / Dissertation (MSc(Agric))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted

The production environment is known to have a large influence on extensively managed beef cows. A better understanding of the relationship between the beef cow and her environment should be useful in the pursuit of improving beef cow efficiency. The influence of the production environment on the efficiency of extensively managed Bonsmara cows was investigated through a series of research objectives. It was found that VEGMAP’s bioregion classification system can be used to describe the South African beef production regions. The environmental characteristics with the potential to influence beef cow efficiency were identified as temperature, rainfall, cation exchange capacity, soil pH, soil organic carbon, soil P and grazing capacity. A dataset was created that contains the historical cow production records for every Bonsmara breeder. GIS tools were then used to link the cow production records with the production region in which the farm is located, as well as the environmental characteristics for that specific location. The combined dataset was then statistically analysed to investigate the research objectives. The influence of the geographic location, production region and breeder on Bonsmara production traits was investigated by cluster analysis and ANOVA. Results from ANOVA indicate that production region has a statistically significant (p < 0.05) influence on production traits. The influence of the breeders on the same production traits was, however, statistically much larger (p < 0.0001) than production region. Bonsmara production traits are therefore influenced to a greater extent by the breeders rather than production environment. Stepwise regression analysis was used to determine the influence of the combined environment on production traits. The combined environment has a statistically significant (p < 0.0001) influence on all the production traits. The results indicate that the extent of the influence of the environment on production change through the growth curve. The environment’s influence was the greatest at weaning (9%) and yearling age (10%). Bonsmara weaning and yearling weights therefore show the largest potential for manipulation through management. The influence of individual environmental characteristics on all the Bonsmara cow production traits was then investigated by the same stepwise regression analysis. Most of the environmental characteristics were found to have a statistically significant (p < 0.0001) influence on the production traits. Rainfall and temperature had the largest influence on Bonsmara production traits. The negative influence of rainfall was attributed to the influence of rainfall on the quality of the grazing. The influence of temperature on production traits was small. The small negative influence of temperature could indicate that Bonsmara cows are well adapted to the main South African beef production regions. Finally, the relationship between Bonsmara cow size and reproduction was investigated by linear regression analysis. Results indicate that larger Bonsmara cows are to some extent more reproductive than smaller cows. The study confirmed that production environment influences beef cow efficiency. Bonsmara breeders however have a much larger influence on the efficiency of their cows through the implementation of management practices and breeding objectives. / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

Many of the beef cattle in the Great Basin area are maintained part or all of the year on rangelands. Most of those going on to desert ranges for only part of the year go on during the late fall, winter, and early spring. It is estimated that 50-60 percent of the 600,000 beef cattle grazing on range lands in Utah graze on the one-fourth million acres of desert or semi-desert sometime during the year.

No description available.

Some cattle producers have reported metabolic disturbances in beef cows fed high levels of broiler litter. Therefore, an experiment was conducted to evaluate mineral metabolism of beef cows fed different levels of broiler litter. Sixty Angus-Hereford crossbred cows ranging in age from 3 to 12 yr were blocked by age, BW, and stage of gestation, and randomly allotted within blocks to three diets: 1) mixed hay, full-fed; 2) 4.1 kg of a mixture of 80% broiler litter and 20% cornmeal plus mixed hay (low-litter diet); and 3) 8.2 kg of the 80% litter and 20% cornmeal mixture plus mixed hay (high-litter diet). Cows fed the litter diets were fed 57 g of magnesium oxide per head per day in the litter-corn mixture. Cows fed the three diets had access to a high-Mg mineral mixture. Experimental diets were fed from January 4, 1995 to April 19, 1995, and calving began on March 15. There were no physical signs of metabolic disturbances in any of the cattle. Blood serum Ca decreased and P levels increased in the cows fed both levels of broiler litter after the first 28 d on experiment. On d 28, average serum Ca values were 8.5 mg / dL for the cows fed hay, compared to 7.9 and 7.6 mg / dL for those fed the low and high levels of litter, respectively (P < .01). The average serum P values were 5.7, 8.2, and 9.1 mg/dL, respectively (P < .01). Generally, serum Ca remained lower and serum P remained higher for the cows fed broiler litter until the end of the winter feeding period (105 d). By mid-summer, serum Ca and P were similar (P > .05) for cows that had been fed the three diets. Serum Mg, Cu, and Zn were not affected by feeding litter. Urinary Ca and Mg, expressed as units per unit of creatinine, did not differ (P > .05) among treatments. Serum parathyroid hormone (PTH) was higher (P < .05) in cows fed the lower level of litter than those fed the higher level in April (105 d). Serum PTH values for cows fed hay were intermediate. Birth weights, rate of gain, and weaning weights of calves did not differ among the three diets. Feeding high levels of broiler litter to beef cows appears to affect serum Ca and P. / Master of Science