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The purpose of this study was to determine the most accurate method of calculating the most probable producing ability (MPPA) of beef cows based on one, two or three records. A preliminary analysis of preweaning records on 9,515 calves from 4 Angus herds enrolled in the Virginia Beef Cattle Improvement Association program was conducted on average daily gain, 205-day weight and index value. Adjusted 205-day weight was selected for further study. To obtain a realistic repeatability value of adjusted 205-day calf weight, needed for calculating MPPA, separate estimates were first obtained for each herd by intraclass correlation. These values were 0.34, 0.00, 0.35 and 0.14. The individual herd sums of squares and degrees of freedom were then pooled to obtain an overall estimate of 0.31. Repeatability was also calculated by the correlation of adjacent records (r = 0.48) and by the regression of the second record on the first (b = 0.51). The pooled intraclass correlation coefficient (0.31) was selected as the best for the calculation of all MPPAs. MPPAs were calculated by the method of Lush (1949), using the dam's progeny record: (1) as a deviation from the herd-year average, and (2) as a deviation from the sire progeny average within years. MPPAs were calculated by both methods based on each of one, tuo and three records and each of these correlated with the average of all subsequent records (maximum of six). The first, second and third MPPA values by the herd-year method yielded correlation coefficients of 0.18, 0.10 and 0.04 with the average of all subsequent records, respectively. Corresponding sire-year correlation coefficients were 0.23, 0.31 and 0.36, respectively. The differences between the correlation coefficients obtained by the two methods for MPPA one, two and three were significant at the level of P < .10, P < .05 and P < .0005, respectively, indicating that the sire-year method is more accurate. The variance was also lower for the sire-year method (427 ± 44.2 pounds) than for the herd-year method (428 ± 55.2 pounds). Thus, the author has concluded from these results that the sire-year method of calculating most probable producing ability is a more accurate measure of the true productivity of beef cows. / Ph. D.

Este trabalho é um estudo comparativo entre as Microrregiões de Avaré e Bragança Paulista, duas regiões do Estado de São Paulo situadas em diferentes unidades geomorfológicas, mas com iguais exigências de produtividade pecuária pelo INCRA (Instituto Nacional de Colonização e Reforma Agrária). Tem como objetivo verificar se estes índices de produtividade pecuária são compatíveis com a potencialidade agropecuária das regiões, definida por suas características físicas, particularmente o relevo. A presença de índices de produtividade não apropriados às características das terras pode penalizar os produtores rurais, que muitas vezes não tem como atingir o grau de produtividade exigido pelo Governo, ou, por outro lado, pode causar graves problemas sócio-econômicos, possibilitando a presença de áreas improdutivas que poderiam ser desapropriadas para a criação de assentamentos rurais de trabalhadores sem-terra. / This work is a comparative study between the Microregions of Avaré and Bragança Paulista, two regions in the State of São Paulo located in different geomorfological units, but with the same productivity demanded from INCRA (The National Institute of Colonization and Agrarian Reform). Its objective is to verify if these rates of cattle productivity are compatible with the potencial in terms of cattle and agriculture of the regions, which were defined for their physical features, particularly the relief. The presence of rates of inappropriate productivity considering the land characteristics can penalize the farmers, who often cannot cope with the level of productivity demanded by the government, or, on the other hand, it can cause major social and economic problems enabling the presence of unproductive areas that could be taken over for the creation of rural settlements for the landless workers.

Este trabalho é um estudo comparativo entre as Microrregiões de Avaré e Bragança Paulista, duas regiões do Estado de São Paulo situadas em diferentes unidades geomorfológicas, mas com iguais exigências de produtividade pecuária pelo INCRA (Instituto Nacional de Colonização e Reforma Agrária). Tem como objetivo verificar se estes índices de produtividade pecuária são compatíveis com a potencialidade agropecuária das regiões, definida por suas características físicas, particularmente o relevo. A presença de índices de produtividade não apropriados às características das terras pode penalizar os produtores rurais, que muitas vezes não tem como atingir o grau de produtividade exigido pelo Governo, ou, por outro lado, pode causar graves problemas sócio-econômicos, possibilitando a presença de áreas improdutivas que poderiam ser desapropriadas para a criação de assentamentos rurais de trabalhadores sem-terra. / This work is a comparative study between the Microregions of Avaré and Bragança Paulista, two regions in the State of São Paulo located in different geomorfological units, but with the same productivity demanded from INCRA (The National Institute of Colonization and Agrarian Reform). Its objective is to verify if these rates of cattle productivity are compatible with the potencial in terms of cattle and agriculture of the regions, which were defined for their physical features, particularly the relief. The presence of rates of inappropriate productivity considering the land characteristics can penalize the farmers, who often cannot cope with the level of productivity demanded by the government, or, on the other hand, it can cause major social and economic problems enabling the presence of unproductive areas that could be taken over for the creation of rural settlements for the landless workers.

One of the more important economic activities in the Altiplano region is raising livestock, the exploitation of cattle, sheep, and llamas which are raised and adapted to the conditions surrounding this activity. Livestock production plays a fundamental role in the economy of farming families by providing them products such as meat, milk, cheese, fiber, skins, and other products that each translate into monetary revenues. The present study was carried out in the community of "Chama 6 de julio," Ingavi Province, Department of La Paz, about 83 km. (51.6 miles) outside of La Paz at an elevation of 3,792 m. (12,440 ft.) above sea level. The annual precipitation is 370 mm. (14.6 inches) and average annual temperature is 12° C (53.6° F). The set objectives of this investigative work were: To evaluate the economic behavior of the livestock production (cattle, sheep, and llamas) at the small ranchers 14 level. To quantify in monetary units the structure of costs and revenues of livestock activity. To carry out a socio-economic analysis of the activity. The statistic parameters used were: measures of means, deviations, and percentages. Techniques used for gathering information include the following: semi-structured interviews, dynamic polls, dialogues, conversations, key informants, and direct observation. In studying the costs and revenues of livestock activity the conventional model of fixed and variable costs was used. The method utilized to evaluate the activity is an adaptation of the economic evaluation expressed by the indicating gauges Cost-Benefit Relationship (RBC) and Annual Investment Profitability (RI). 42 families dedicated to agricultural and livestock activity were involved in the study. They were functionally classified according to the number of cattle that they have on their land, a classification that resulted in four groups. The first group contained families possessing from 4 to 6 cattle; the second, from 7 to 9; the third, from 10 to 12; and the fourth, the families with 13 to 15 cattle. Also, the number of samples for each class was calculated to be 5 families. As livestock activity is the most important for families in this community, these families have most of their money invested in their herds, investments ranging from 73% to 86% of all their active livestock investments. The other 14% to 27% of their investment is in the livestock infrastructure, tools, materials, and equipment. The amount of land possessed by families in this community ranges from 8 to 40 hectacres (19.8 to 98.8 acres). The meat (cattle, sheep, and llama) is the most important product for commercial purposes. Accordingly, families from class IV achieved the highest production with 812 kg. (180.7 lbs) per year, followed by classes III and II. The lowest annual amount came from families grouped into class I with only 235 kg. (518 lbs). Another product of utmost importance after meat is cheese for which the families of class IV were those that had the highest annual production with 476 units, with an average weight of 0.6 kg (1.3 lbs). They were followed by families in classes III and I. Finally, the families in class II achieved the smallest output with 337 units. 69% to 79% of the total production of meat and cheese is destined for market. The families consume only 10% to 31% of what is produced. Variable costs represent 87.25% of the total expenses. On the other hand, fixed costs amount to only 12.73% of the total. Labor represents the greatest expense, reaching an average of 71.17% of the total expense. Relative to gross annual revenue, families in class IV reached the highest average numbers with 7,996.00 Bs. (Bolivianos). The lowest gross annual revenues correspond to those in class I with only 3,124.00 Bs. Classes III and II occupy intermediate positions between both former classes. Comparing the sources of gross annual revenue, cattle meat occupies the greatest portion with 40.81%. This is followed by cheese production, lamb, and llama meat with 30.84%, 23.30%, and 2.17% respectively. At the same time, cattle meat and cheese provide these farming families with 71.65% of their total gross annual revenue. The net annual revenues are positive only for families in classes IV and III with numbers at 312.00 and 156.00 Bs. On the other hand, classes II and I have negative net revenues at -3,039.00 and -2,455.00 Bs. The indicative Cost-Benefit Relationship (RBC) shows viability of the activity for families from classes IV and III with figures of 1.04 and 1.02. It is not as viable for families in classes II and I with numbers at 0.62 and 0.50. Estimates provided by the annual investment profitability (RI) are only satisfactory for those in classes IV and III with percentages of 4.6% and 2.13%. Unsatisfactory percentages result for classes II and I with -35.45% and -49.31%. According to the results obtained for the four classes, livestock activity carried out by farming families does not provide an acceptable profitability, even for families that have greater numbers of livestock (more than 12 cattle). It would be much less profitable for the families that have smaller herds of livestock.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The effect of Acid Buf and combinations of Acid Buf and Sodium bicarbonate in dairy cow diets on production response and rumen parameters The objective of this study was to determine the effect of Acid Buf alone, or in combination with sodium bicarbonate, on milk production, milk composition and selected rumen parameters. A high concentrate TMR, formulated to be potentially acidotic, was used to construct four dietary treatments in which Acid Buf (AB), the skeletal remains of the seaweed Lithothamnium calcareum, was used alone or in combination with sodium bicarbonate (BC). The diets contained 3.5 g/kg of AB (Treatment 1) or 1.75 g/kg of AB and 1.75 g/kg of BC (Treatment 2) or 3.5 g/kg of AB and 3.5 g/kg of BC (Treatment 3) or 3.5 g/kg of AB and 5.2 g/kg of BC (Treatment 4). The response to treatment was determined using eight ruminally cannulated lactating Holstein cows randomly allocated to treatments according to a 4 x 4 (n=2) Latin square design, with four treatments and four periods. The total experimental period was 100 days in which every cow received each diet for a period of 18 days prior to a data collection period of 7 days. Rumen pH was monitored continuously over 2 days using a portable data logging system and in-dwelling electrodes. Samples of rumen fluid were collected for volatile fatty acid (VFA) analyses. During each data collection period, milk production was recorded twice daily for 7 days, whereas milk was sampled twice daily for five consecutive days for component analysis. Cows were fed ad libitum and dry matter intake was recorded individually. Treatment had no significant effect on milk production, milk composition or feed intake. Ruminal pH profiles of all the treatments indicated that the diets were well buffered. Average pH over 24 hours was 6.0, 6.1, 6.1 and 6.2 for Treatments 1, 2, 3 and 4, respectively. The pH did not go below 5.8 for any of the treatments and increasing levels of sodium bicarbonate increased the diurnal profile such that at the highest level (Treatment 4), the pH profile ranged from 6.1 to 6.5. Although not significant, Treatment 1 (Acid Buf alone) numerically resulted in the highest milk output without compromising milk quality. It is proposed that high rumen pH may impact negatively on milk output by increasing the acetate:propionate ratio to the detriment of rumen efficiency. Treatment had no significant effect on total VFA concentration, but there seemed to be a tendency for increased total VFA concentration as the level of sodium bicarbonate increased. The acetate:propionate ratio of Treatment 1 (2.91) was significantly lower than Treatment 4 (3.65) (P<0.05). The use of buffers which react to increasing acidity in the rumen may therefore provide an efficient, safe solution to rumen acidosis. This study confirmed previous results indicating that a daily intake of 80 g of Acid Buf by cows receiving high concentrate diets would support high milk production without compromising milk solids contents. / AFRIKAANSE OPSOMMING: Die effek van Acid Buf en kombinasies van Acid Buf en Natriumbikarbonaat in melkkoeidiëte op melkproduksie, melksamestelling en rumenparameters Die doel van die studie was om die invloed van Acid Buf alleen, of in kombinasie met natriumbikarbonaat, in melkbeesdiëte op melkproduksie en melksamestelling, asook op bepaalde rumenparameters, te bepaal. ‘n Volledige dieet met ‘n hoë kragvoerinhoud, wat geformuleer is om potensieel asidoties te wees, is gebruik om vier dieetbehandelings saam te stel waarin Acid Buf (AB), die skeletoorblyfsels van die seegras Lithothamnium calcareum, alleen of in kombinasie met natriumbikarbonaat (BK) gebruik is. Een basale diet is dus geformuleer en die behandelingsdiëte het onderskeidelik 3.5 g/kg AB (Behandeling 1) of 1.75 g/kg AB en 1.75 g/kg BK (Behandeling 2) of 3.5 g/kg AB en 3.5 g/kg BK (Behandeling 3) of 3.5 g/kg AB en 5.2 g/kg BK (Behandeling 4) bevat. Agt rumen-gekannuleerde lakterende Holsteinkoeie is ewekansig aan die behandelings toegeken in ‘n 4 x 4 (n=2) Latynse vierkantontwerp met vier behandelings en vier periodes. Die totale eksperimentele periode was 100 dae, waartydens elke koei elke behandeling vir 18 dae ontvang het voor die datakolleksieperiode van 7 dae. Rumen pH is voortdurend, elke vier minute, oor ‘n twee-dae periode gemeet met behulp van draagbare dataloggers en pH elektrodes wat binne-in die rumen gesetel was. Rumenvloeistof is versamel vir die bepaling van vlugtige vetsuurkonsentrasies. Gedurende elk van die datakolleksieperiodes is die melkproduksie twee maal per dag geneem vir sewe agtereenvolgende dae en melkmonsters is tweemaal per dag versamel vir vyf agtereenvolgende dae vir komponent–analise (samestelling?). Koeie is ad libitum gevoer en voerinnames is individueel bepaal. Die behandelings het geen betekenisvolle invloed op melkproduksie, melksamestelling of voerinnames gehad nie. Rumen pH profiele van al die behandelings het aangedui dat die diëte goed gebuffer was. Die gemiddelde pH oor 24 uur was 6.0, 6.1, 6.1 en 6.2 vir Behandeling 1, 2, 3 en 4, onderskeidelik. Die pH het nie onder 5.8 gedaal vir enige van die behandelings nie en die toenemende vlakke van natriumbikarbonaat het ‘n verhoging in die daaglikse pH-profiele tot gevolg gehad. By die hoogste buffervlakke (Behandeling 4) het die pH-profiel tussen 6.1 en 6.5 gevarieer. Hoewel nie betekenisvol nie, het Behandeling 1 (slegs Acid Buf) numeries die hoogste melkproduksie getoon, sonder dat melkkwaliteit beïnvloed is. Dit is voorgestel dat te hoë rumen pH ‘n nadelige impak op melkproduksie kan hê, as gevolg van ‘n verhoogde asetaat:propionaat verhouding wat rumen doeltreffendheid benadeel. Behandelings het geen betekenisvolle invloed op totale vlugtige vetsuurkonsentrasies gehad nie, maar daar was ‘n neiging vir hoër totale vlugtige vetsuurkonsentrasies namate die vlakke van natriumbikarbonaat verhoog het. Die asetaat:propionaat verhouding van Behandeling 1 (2.91) was betekenisvol laer as dié van Behandeling 4 (3.65). Die gebruik van buffers wat reageer op toenemende suurheidsgraad kan dus aangewend word as ‘n doeltreffende en veilige oplossing vir rumen asidose. Die studie het bevestig dat ‘n daaglikse inname van 80 g Acid Buf deur koeie wat ‘n hoë kragvoerdieet ontvang, hoë melkproduksie ondersteun sonder dat melksamestelling nadelig beïnvloed word.