Breeding objectives and selection strategies for broiler production.

Author(s):  
D. Emmerson
2015 ◽  
Vol 55 (12) ◽  
pp. 1437 ◽  
Author(s):  
S. Hermesch ◽  
L. Li ◽  
A. B. Doeschl-Wilson ◽  
H. Gilbert

Pig breeding programs worldwide continue to focus on both productivity and robustness. This selection emphasis has to be accompanied by provision of better-quality environments to pigs to improve performance and to enhance health and welfare of pigs. Definition of broader breeding objectives that include robustness traits in addition to production traits is the first step in the development of selection strategies for productivity and robustness. An approach has been presented which facilitates extension of breeding objectives. Post-weaning survival, maternal genetic effects for growth as an indicator of health status and sow mature weight are examples of robustness traits. Further, breeding objectives should be defined for commercial environments and selection indexes should account for genotype by environment interactions (GxE). Average performances of groups of pigs have been used to quantify the additive effects of multiple environmental factors on performance of pigs. For growth, GxE existed when environments differed by 60 g/day between groups of pigs. This environmental variation was observed even on well managed farms. Selection for improved health of pigs should focus on disease resistance to indirectly reduce pathogen loads on farms and on disease resilience to improve the ability of pigs to cope with infection challenges. Traits defining disease resilience may be based on performance and immune measures, disease incidence or survival rates of pigs. Residual feed intake is a trait that quantifies feed efficiency. The responses of divergent selection lines for residual feed intake to various environmental challenges were often similar or even favourable for the more efficient, low residual feed intake line. These somewhat unexpected results highlight the need to gain a better understanding of the metabolic differences between more or less productive pigs. These physiological differences lead to interactions between the genetic potential of pigs for productivity and robustness and the prevalence of specific environmental conditions.


Advancement in sequencing technologies has contributed towards identification and development of different types of molecular markers. Molecular plant breeding has contributed to a more comprehensive understanding of molecular markers and their role in identifying the genetic diversity within the crop plants. Marker-assisted breeding is basically the application of molecular markers, in combination with linkage maps and genomics, to alter and improve plant traits on the basis of genotypic assay. Several modern plant breeding strategies were developed which include marker-assisted selection (MAS), marker-assisted backcrossing (MABC), marker-assisted recurrent selection (MARS), and genome-wide selection (GWS) or genome selection (GS). The selection of right type of molecular markers is usually dependent on the breeding objectives. Similarly, selection strategies of molecular markers for qualitative and quantitative characters may differ. The procedure followed for marker assisted selection under various breeding objectives and conditions, for qualitative and quantitative traits are discussed in this chapter.


Author(s):  
Lindsey M. Kitchell ◽  
Francisco J. Parada ◽  
Brandi L. Emerick ◽  
Tom A. Busey

2019 ◽  
Vol 17 (1) ◽  

Background: Commercial broiler is a rapidly growing sector in Bangladesh. The broilers are supplied with the balanced ration prepared from a number of ingredients which are not available uniformly throughout the years. On the other hands, manufactured feeds are costly and inconvenient for the rural farmers. This study is undertaken to use unconventional feed ingredients aiming to decrease the broiler production cost. Method: A total of ninety-nine day- old broiler chicks (Hubbard) of either sex were used in this study in 3 treatment groups to assess processed unconventional feed item (shoti, blood meal, poultry dropping and molasses) on growth and profitability upon rearing for 60 days. Broilers were reared in dip litter system and were fed ad libitum on conventional and unconventional diet dividing into 3 treatment diets namely, treatment diet 1 (T1: Conventional as control), treatment diet 2 (T2: unconventional with blood meal and shoti), and treatment diet 3 (T3: unconventional with blood meal, shoti, poultry droppings and molasses) throughout the trial period. Treatment group 1 (T1) was used as control. Results: Broilers fed on control diet (conventional feed) achieved higher (P<0.01) body weight, while the broilers offered diets with the highest amount of unconventional feed had the lowest body weight. Increased (P<0.01) feed intake was observed during 21days and 49 days of age when broilers fed diets with the supplementation, but no significant differences were found among the groups in terms of feed consumption during 33 day of age. FCR differed significantly (P<.01) throughout the trial period with the broilers fed diets without supplementation of unconventional feed item had the superior FCR than the others. Mortality rate was 6.06%,9.09%, and 9.09% in treatment group I, treatment group II, and treatment group III respectively while live weights, feed conversion and feed consumption was unaffected by all the dietary groups with/without incorporation of unconventional feed item up to day 60 days of age. Statistically significant (P<0.01) decreased live weight was observed among the treatment groups in 60-day-old birds. Productivity and cost-benefit analysis were performed. Conclusion: Use of unconventional feed ingredients in broiler production greatly reduces the feed cost with little hampering the growth rate and hence, it is profitable for the farmers.


2020 ◽  
Author(s):  
Rui Sun ◽  
Disa Sauter

Getting old is generally seen as unappealing, yet aging confers considerable advantages in several psychological domains (North &amp; Fiske, 2015). In particular, older adults are better off emotionally than younger adults, with aging associated with the so-called “age advantages,” that is, more positive and less negative emotional experiences (Carstensen et al., 2011). Although the age advantages are well established, it is less clear whether they occur under conditions of prolonged stress. In a recent study, Carstensen et al (2020) demonstrated that the age advantages persist during the COVID-19 pandemic, suggesting that older adults are able to utilise cognitive and behavioural strategies to ameliorate even sustained stress. Here, we build on Carstensen and colleagues’ work with two studies. In Study 1, we provide a large-scale test of the robustness of Carstensen and colleagues’ finding that older individuals experience more positive and less negative emotions during the COVID-19 pandemic. We measured positive and negative emotions along with age information in 23,629 participants in 63 countries in April-May 2020. In Study 2, we provide a comparison of the age advantages using representative samples collected before and during the COVID-19 pandemic. We demonstrate that older people experience less negative emotion than younger people during the prolonged stress of the COVID-19 pandemic. However, the advantage of older adults was diminished during the pandemic, pointing to a likely role of older adults use of situation selection strategies (Charles, 2010).


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