Modelling genetic improvement of Pabna cattle in Bangladesh

Figures & data

Table 1. Simulated traits, their means, standard deviations, EVs and age effects.

Traits	Average^a,b	Phenotypic standard deviation (kg)	EVs (US$ per unit)^b	Age effects
				10 year	9 year	8 year	7 year	6 year	5 year	4 year
Milk yield (kg)	1697.4	262.50	0.32	−128	−102	−51	0	0	−64	−256
Fat yield (kg)	77.7	9.10	−0.52	−6.03	−4.83	−2.41	0	0	−3.21	−12.07
Protein yield (kg)	71.4	8.70	−0.29	−5.43	−4.34	−2.20	0	0	−2.72	−10.86
Liveweight (kg)	259.4	16.40	−0.39	−11.31	−2.49	−4.41	0	0	−18.69	−30.57
Longevity (days)	2752	129.30	0.88	0	0	0	0	0	0	0

^aKhan et al. (2012).

^bKhan (2009).

Table 2. Genotypic and phenotypic correlations between traits used in the model (Khan, 2009).

Traits	MY	FY	PY	Lwt	Longevity
MY	0 . 26	0.57	0.46	0.16	0.05
FY	0.63	0 . 27	0.82	0.66	0.13
PY	0.59	0.79	0 . 25	0.59	0.04
Lwt	0.13	0.67	0.65	0 . 40	0.07
Longevity	0.09	0.13	0.07	0.02	0 . 05

Notes: MY = milk yield; FY = Fat yield; PY = Protein yield; Lwt = Liveweight. Genotypic correlations are shown above the diagonal, heritabilities on the diagonal (bold) and phenotypic correlations below the diagonal.

Table 3. Population biological and technical parameters for the simulation study.

Parameters	PAT	PT
(a) Population parameters
Number of cows	10,000	10,000
Bull to cow ratio
For natural mating		1:20
For artificial mating	1:2000	1:2000
Percentage of bull dams	1.5
Percentage of replacement	20	20
(b) Survival and reproduction
Calving rate (%)	65	65
Survivability (%)	88	86
Calving interval (years)	1.3	1.3
Male and female calves ratio	1:1	1:1
(c) Artificial insemination
Number of straws/young bull	4000	4000
Number of straw required/pregnancy	2	3
Size of progeny group per testing bull under natural mating		1: 24

Table 4. Mean and standard error (se) of genetic gain (Δg) in US$ per year and R² value of milk traits, liveweight and longevity of the simulated cow population under PAT and PT selection schemes with a selection objective for milk merit.

Traits	Selection for milk merit
	PAT									PT
	From year 1 to 9			From year 9 to 20			From year 1 to 20			From year 1 to 9			From year 9 to 20			From year 1 to 20
	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2
MY	29.4^b	0.70	0.81	4.20^a	0.25	0.16	15.3^b	0.13	0.74	22.50^a	0.97	0.80	4.56^b	0.31	0.21	13.5^a	0.45	0.80
FY	0.69^b	0.03	0.89	0.07	0.02	0.12	0.29	0.03	0.70	0.60^a	0.10	0.70	0.11	0.05	0.22	0.24	0.02	0.66
PY	0.61^b	0.03	0.89	0.11	0.02	0.29	0.27	0.03	0.76	0.50^a	0.07	0.80	0.07	0.07	0.11	0.23	0.01	0.69
Lwt	0.50	0.10	0.78	0.05^a	0.03	0.08	0.19^a	0.03	0.66	0.50	0.12	0.90	0.10^b	0.04	0.10	0.27^b	0.05	0.75
Lg	1.30	0.20	0.65	1.20^b	0.08	0.56	1.06^a	0.12	0.74	1.20	0.24	0.80	0.97^a	0.28	0.29	1.50^b	0.18	0.79

Notes: MY = milk yield; FY = fat yield; PY = protein yield; Lwt = liveweight; Lg = longevity. Means with superscript a and b are different at 5% level of significance between breeding schemes.

Table 5. Mean and standard error (se) of genetic gain (Δg) in US$ per year and R² value of milk traits, liveweight and longevity of the simulated bull population under PAT and PT selection schemes with a selection objective for milk merit.

Traits	Selection for milk merit
	PAT									PT
	From year 1 to 9			From year 9 to 20			From year 1 to 20			From year 1 to 9			From year 9 to 20			From year 1 to 20
	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2	Δg	se	R^2
MY	25.41^b	0.56	0.69	8.66^b	0.58	0.68	15.08^b	0.33	0.90	19.98^a	0.65	0.81	6.32^a	0.77	0.23	12.89^a	0.63	0.55
FY	0.51	0.08	0.93	0.21	0.07	0.49	0.27	0.10	0.94	0.44	0.08	0.86	0.22	0.04	0.33	0.26	0.02	0.54
PY	0.67^b	0.15	0.83	0.20	0.05	0.39	0.25^b	0.04	0.84	0.40^a	0.09	0.43	0.25	0.03	0.34	0.17^a	0.05	0.45
Lwt	0.26	0.11	0.56	0.22	0.06	0.38	0.27	0.01	0.74	0.21	0.10	0.11	0.31	0.14	0.47	0.38	0.10	0.48
Lg	1.25^a	0.17	0.95	1.81^a	0.39	0.62	2.18^a	0.23	0.80	2.30^b	0.72	0.76	2.32^b	0.47	0.47	2.86^b	0.14	0.63

Notes: Descriptions of all items are in the footnote of Table 4. Means with superscript a and b are different at 5% level of significance between selection objectives.

Figure 1. Average economic merit with standard deviation (bar) for milk yield under PAT and PT breeding scheme with different selection objectives for all cows born in a particular year.

Table 6. Correlated response (CR_Y) with longevity and other traits in consideration of two breeding schemes within three selection objectives.

Traits	Selection strategy
	Selection for milk merit		Selection for milk and survivability merit		Selection for total merit
	PAT	PT	PAT	PT	PAT	PT
MY	2.31	2.51	4.93	4.77	5.72	4.88
FY	0.07	0.09	0.16	0.19	0.16	0.18
PY	0.04	0.07	0.12	0.21	0.11	0.14
Lwt	0.04	0.08	0.12	0.22	0.07	0.26

Note: Descriptions of all items are in the footnote of Table 4.

Khan MKI, Blair HT, Lopez-Villalobos N. 2012. Lactation curves of different cattle breeds under cooperative dairying conditions in Bangladesh. J Appl Anim Res. 40:179–85. Available from: www.tandfonline.com/dx.doi.org/10.1080/09712119.2011.645039.

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Khan MKI. 2009. Development of models for the genetic improvements of dairy cattle under cooperative dairying conditions in Bangladesh. PhD thesis, IVABS, Massey University, New Zealand. Available from: muir.massey.ac.nz/bitstream/10179/1378/1/02_whole.pdf.

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