RESUMO
We hypothesised that use of reproductive technologies (RTs) would result in increases in economic and genetic gains of a dairy cattle breeding programme. A deterministic approach was used to compare RTs that can be utilised to increase dairy cattle productivity and profitability in Kenya. These were artificial insemination (AI), embryo transfer (ET) using old (ETOB) and young (ETYB) bulls and in vitro fertilisation (IVF). Natural mating (NAm) was assumed to be the standard reproduction practice in Kenya against which the genetic and economic efficiencies of the RTs were compared. A three tiers open nucleus system was assumed to describe the dairy cattle breeding programme in Kenya. It was open to use of imported semen in the nucleus. The nucleus was assumed to be closed to upward movement of live animals. This is the common practice in Kenya where large farms act as the nucleus from which the multipliers (medium-sized farms) buy replacement stock and subsequently sell replacement animals to the commercial sector (smallholder farms). The increase in monetary gain ranged between 11% when AI was used and 184% when utilising either juvenile ET or IVF. The ETYB and IVF resulted in similar economic and genetic responses for all comparison criteria. The generation interval reduced by between 0.8% in AI and 47% in ETYB and IVF technologies. The respective milk yield (MY) and daily weight gain (dWG) responses were between 25 to 150% and 0 to 110% for the AI and ETYB and IVF.
Assuntos
Cruzamento/métodos , Bovinos/genética , Técnicas de Reprodução Assistida/veterinária , Animais , Cruzamento/economia , Indústria de Laticínios/métodos , Transferência Embrionária , Fazendas , Feminino , Inseminação Artificial/veterinária , Quênia , Masculino , Leite , Modelos Teóricos , Reprodução , Técnicas de Reprodução Assistida/economia , SêmenRESUMO
This study aimed at testing the efficacy and safety of Dacryodes edulis plant parts in diets fed to chicken. The plant has potential for use as a natural prebiotic to substitute the conventionally used antibiotic growth promoters in poultry production. Phytochemical analyses of the plant leaves, stem, and bark combination (stembark) and seed powders from the D. edulis were carried out. The powder from the three D. edulis plant parts were used as supplement in formulating six experimental diets tested in this study. The diets were TL0Ed (0.5% leaves powder), TL1Ed (1.0% leaves powder), TB0Ed (0.5% stembark powder), TB1Ed (1.0% stembark powder), TS0Ed (0.5% seeds powder), and TS1Ed (1.0% seeds powder). Besides, a positive (T+ positive control; 0.5-g oxytetracycline as recommended by the manufacturer) and a negative (T- negative control; having no commercial antibiotic and no plant supplement) diets were prepared for comparison purposes. The diets were fed to a total of 288 dual-purpose chicken for a period of 14 weeks. The chicken growth and body composition characteristics, blood chemistry, and microbiota count were collected and used as indicators of the plant parts efficacy and safety. The analysis of the D. edulis plant parts significantly differed (P ≤ 0.05) in their phytochemical contents. The initial body weight and feed conversion efficiency ratios were not significantly different (P ≥ 0.05) between and among treatment groups. However, significant differences (P ≤ 0.05) were detected in the feed intake and body weight gain at eighth week. Live weight at eighth week was significantly different (P ≤ 0.05) with its values ranging between 503.32 and 614.93 g for treatments TL1Ed and TNeg-, respectively. The dietary treatment of D. edulis leaves, stembark, and seed powder at the two inclusion levels significantly (P ≤ 0.05) decreased the colonies forming unit of Escherichia coli and Salmonella sp. as compared with negative control treatment in the eighth week phase. The level of glucose, total cholesterol, triglycerides, aspartate aminotransferase, alanine amino transferase, alkaline phosphatase, and the packed cell volume did not differ significantly (P ≥ 0.05) between and among dietary D. edulis treatments. The findings from this research provide crucial information on the efficacy and safety of D. edulis plant parts. This is an important step in testing the potential of the plant in use as a prebiotic in chicken feeds production.