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Dairy, Veterinary & Animal Research

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Received: January 01, 1970 | Published: ,

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Abstract

Data on part lactation yields (50-days, 70-days, 1^st 100, 2^nd 100 days, 3^rd 100, 182 days) and 305-days milk yield comprising all lactations of 378 Jersey crossbred cattle, maintained at the Eastern Regional Station of ICAR-NDRI, Kalyani over a period of 35 years (1982-2016) were collected to study the effect of genetic and non-genetic factors on lactation persistency of cattle. Five lactation persistency indices of animals (P₂₁, P₃₁, P₃₂, P₄ and P₅) were calculated using ratio method. Least squares analysis of variance with fitting constant was applied to determine the effect of genetic and non-genetic factors on different persistency indices of Jersey crossbred cattle. In the present study, the least squares means of five different measures of lactation persistency viz., P₂₁, P₃₁, P₃₂, P₄ and P₅ were 0.76±0.01, 0.59±0.01, 0.80±0.01, 4.70±0.06 and 1.30±0.02 respectively. Random effect of sire showed significant (P<0.05) influence on some of the persistency indices (viz., P₂₁, P₄ and P₅). Period of calving had significant (P<0.01) effect on all the five persistency indices. Season of calving showed significant (P<0.01) influence on P₂₁, P₃₁, P₄ and P₅. Cows that calved during rainy season showed the highest persistency in milk yield. Parity of animals had significant effect on all measures of persistency indices and cows in first parity showed the highest persistency as compared to cows of later parities. Genetic groups of animals did not show significant (P>0.05) effect on any of the persistency indices considered for this study.

Keywords: lactation persistency, environmental factors, crossbred cattle

Introduction

Lactation persistency, an economically important trait of dairy animal, can be defined as the ability of a cow to continue milk production at a high level after the peak yield.¹ Cows that sustain high rate of milk secretion for longer period in lactation are known as persistent producers while other goes dry or drop the yield within a few weeks and hence called as non-persistent. High lactation persistency is associated with slow rate of decline in production, whereas low lactation persistency is associated with a rapid rate of decline. In any dairy industry, animals producing milk at a high level of persistency are considered as economical as it will lead to reduction and stabilization of production cost and ultimately yield more profit. The persistency of lactation is affected by various environmental factors such as genetic group, sire effect, herd management, lactation number, feeding, gestation and season of calving of animals. Therefore, the present study was undertaken to determine the effect of genetic and non-genetic factors on lactation persistency of crossbred cattle.

Materials and methods

The present study was conducted on Jersey crossbred cows to identify the genetic and non-genetic sources of variations in persistency indices of milk production. Data on part lactation yields (50-days, 70-days, 1^st 100, 2^nd 100 days, 3^rd 100, 182 days), 305-days milk yield comprising all lactations of 378 Jersey crossbred cattle, maintained at the Eastern Regional Station of ICAR-NDRI, Kalyani over a period of 35 years (1982-2016) divided into 7 periods were collected and used. Each year was divided into 3 seasons Viz. winter (November– February), summer (March–June) and Rainy (July–October). Animals were divided into 10 genetic groups depending upon their level of exotic inheritance. Five lactation persistency indices of animals (P₂₁, P₃₁, P₃₂, P₄ and P₅) were calculated using ratio method as follows:

P₂₁ is the persistency index No. 1=2^nd 100 days milk yield/1st 100 days milk yield,
P₃₁ is the persistency index No. 2=3^rd 100 days milk yield/1st 100 days milk yield,
P₃₂ is the persistency index No. 3=3^rd 100 days milk yield/2^nd 100 days milk yield,
P₄ is the persistency index No. 4=305 days milk yield/50 days milk yield and
P₅ is the persistency index No. 5=(182 days milk yield –70 days milk yield)/70 days milk yield. Since, the data were distributed unequally and disproportionately among sub-classed, so, data were analyzed by using the LSML (least squares maximum likelihood) computer programme.

The following mixed model was used:

$Y_{i j k l m n} = μ + B_{i} + P_{j} + {(P a)}_{k} + S_{l} + {(G G)}_{m} + e_{i j k l m n}$ ,

Where,

Y_ijklmn= n^th observation on lactation persistency of crossbred cow calved during j^thperiod, k^thparity, l^thseason and belonging to m^th genetic group.

µ = Overall mean

B_i= Random effect of i^th sire

P_j= Fixed effects of j^thperiod of calving (k= 1, 2, 3……7)

(Pa)_k= Fixed effects of k^th parity of animal (l=1, 2,3……7)

S_l= Fixed effects of l^th season of calving (j=1, 2, 3)

(GG)_m= Effect of m^th genetic group (m=1,2,3…...10)

e_jklmn= Random error ~ NID (0, σ²_e)

Results and discussion

The overall least squares means of P₂₁, P₃₁, P₃₂, P₄ and P₅ were 0.76±0.01, 0.59±0.01, 0.80±0.01, 4.70±0.06 and 1.30±0.02 respectively. Random effect of sire showed significant (P<0.05) influence on P₂₁, P₄ and P₅. Period of calving had significant (P<0.05) effect on all the five indices of lactation persistency. Period of calving had significant (P<0.05) effect on all the five indices of lactation persistency of Jersey crossbred cows (Table 1). Similar significant effect of period of calving on lactation persistency of cattle was observed by Kumar et al.,² in Karan Fries cattle, Garudkar et al.,³ in Phule Triveni cattle and Sharma et al.,⁴ in HF cattle. In this study, there was no definite trend for lactation persistency over the periods but animals calved during 1992-1996 and 2002-2006 had comparatively higher persistency whereas, the cows that calved in 2007-2011 and 2012-2016 had lower persistent than others. Moreover, all the persistency indices of animals exhibited constant trend in the later periods, which may be ascribed as same managemental practices in the herd during the periods. The parity of animal had significant (P<0.05) effect on all the persistency indices of milk production (Table 1). The highest lactation persistency was observed in Jersey crossbred cows of first parity in the present study. Similar significant effect of parity of cow on lactation persistency was observed by various workers^5‒8 The reason of cows of first parity were more persistent in this study may be explained as presence of more number of secretary cells in mammary gland, which maintain their secretary activity for a longer duration in first lactation as compared to subsequent lactations where although the amount of milk secretion by each secretary cell is increased but it fails to maintain their secretary activity for a longer duration and finally get sloughed off at early stage of lactation. Season of calving also showed significant (P<0.05) effect on P₂₁, P₃₁, P₄ and P₅ persistency measures. Similar significant effects of season of calving on lactation persistency was observed by Kumar et al.,² Yilmaz et al.,⁸ & Guler et al.,⁹ in different breeds of cattle. In the present study, rainy calves were more persistent than summer and winter calves. The reason may be due to sufficient availability of green fodder during rainy season which is followed by a comfortable temperature of ensuing winter season post peak yield. Cows calved during summer season were least persistent which may be due to increased temperature with high humidity. These findings were in agreement with that of Kumar et al.,² who reported highest persistency in rainy calves in Karan-Fries cattle. In the present study, genetic group of animals did not show significant effect on persistency indices of milk production. Although cows with 50 % Jersey inheritance showed more persistency as compared to cows with less than or more than 50 % Jersey inheritance. Sharma et al.⁴ also observed non-significant effect of genetic group of animals on persistency indices of milk production in HF crossbred cattle.

Effects

P21

P31

P32

Overall Mean

0.76±0.01

(1291)

0.59±0.01

(977)

0.80±0.01

(985)

4.70±0.06

(980)

1.30±0.02

(1311)

Period of Calving

Pd1 (1982-86)

0.73^abc±0.05 (52)

0.60^bc ±0.05

(41)

0.98^a ±0.07

(43)

4.71^abc ±0.27 (43)

1.25^abc ±0.08 (51)

Pd2 (1987-91)

0.80^ab ±0.03

(133)

0.62^ab ±0.04

(105)

0.86^ab±0.05 (106)

4.92^ab ±0.19

(104)

1.38^ab ±0.06

(138)

Pd3 (1992-96)

0.80^ab ±0.02

(185)

0.61^ab ±0.02

(151)

0.79^bc ±0.03 (152)

5.04^a ±0.13

(150)

1.40^a ±0.04 (184)

Pd4 (1997-01)

0.76^abc ±0.02 (227)

0.56^abc ±0.02 (186)

0.76^bc ±0.03 (187)

4.60^bc ±0.11

(185)

1.31^ab±0.03

(230)

Pd5 (2002-06)

0.81^a ±0.02 (194)

0.63^a ±0.03 (143)

0.79^bc ±0.03 (145)

4.91^ab ±0.13 (146)

1.35^ab ±0.04 (197)

Pd6 (2007-11)

0.72^bc ±0.03

(241)

0.52^c±0.03

(173)

0.70^c ±0.04

(174)

4.45^bd ±0.17 (174)

1.23^bc ±0.05

(247)

Pd7 (2012-16)

0.69^c ±0.04

(295)

0.57^abc ±0.05 (178)

0.71^bc ±0.06 (178)

4.27^c ±0.22

(178)

1.16^c ±0.07

(264)

Parity of animal

0.80^a ±0.01

(374)

0.67^a ±0.02

(300)

0.85^a ±0.02

(301)

5.00^a ±0.09

(298)

1.36^a ±0.03

(381)

0.76^b ±0.01

(295)

0.59^b ±0.01

(209)

0.80^a ±0.02

(215)

4.64^b ±0.08

(214)

1.27^b ±0.03

(299)

0.76^b ±0.01

(220)

0.58^b ±0.01

(164)

0.78^b ±0.02

(164)

4.63^b ±0.09

(165)

1.29^ab ±0.03

(222)

0.75^b ±0.02

(146)

0.57^b ±0.02

(110)

0.82^a±0.02

(112)

4.48^b ±0.09

(109)

1.29^ab ±0.03

(146)

0.76^b ±0.02

(109)

0.57^b ±0.02

(86)

0.78^ab ±0.03 (85)

4.72^b ±0.10

(86)

1.31^ab ±0.03

(110)

0.74^b ±0.02

(69)

0.57^b±0.02

(54)

0.80^a ±0.03

(54)

4.72^ab ±0.13

(55)

1.28^ab ±0.04

(72)

0.75^b ±0.02

(78)

0.56^b ±0.03

(54)

0.76^b ±0.04

(54)

4.71 ±0.15

(53)

1.29^ab ±0.04

(81)

Season of calving

S1 (Winter)

0.77^a ±0.01

(418)

0.56^b ±0.01

(325)

0.78±0.02

(328)

4.64^b ±0.07

(327)

1.32^a ±0.02

(422)

S2 (Summer)

0.72^b ±0.01

(440)

0.57^b ±0.01

(341)

0.81±0.02

(341)

4.59^b ±0.07

(336)

1.25^b ±0.02

(446)

S3 (Rainy)

0.79^a ±0.01

(433)

0.64^a ±0.01

(311)

0.81±0.02

(316)

4.87^a ±0.07

(317)

1.32^a ±0.02

(443)

Genetic group of animal

G-1 (½ J × ½ RS)

0.78±0.02

(99)

0.60±0.02

(81)

0.80±0.03

(81)

4.77±0.11

(81)

1.32±0.04

(99)

G-2 (½ J × ½ T)

0.73±0.02

(243)

0.59±0.03

(178)

0.83±0.04

(183)

4.73±0.14

(184)

1.26±0.05

(245)

G-3 (≥ 50 % to 62.5% J)

0.77±0.02

(229)

0.57±0.02

(172)

0.79±0.02

(173)

4.69±0.10

(171)

1.35±0.03

(230)

G-4 (1/2 J×1/4RS ×1/4T)

0.79±0.02

(192)

0.62±0.02

(147)

0.79±0.03

(146)

4.87±0.11

(145)

1.35±0.03

(195)

G-5 (1/2J × 1/4RS × 1/8T × 1/8D)

0.75±0.02

(110)

0.58±0.02

(73)

0.79±0.03

(73)

4.75±0.12

(73)

1.29±0.04

(112)

G-6 (½ J×⅜ RS×⅛ T)

0.78±0.02

(111)

0.59±0.02

(80)

0.78±0.03

(79)

4.89±0.13

(79)

1.36±0.04

(114)

G-7 (Misc. 50% J)

0.79±0.03 (75)

0.59±0.03

(61)

0.79±0.04

(64)

4.71±0.16

(64)

1.31±0.05

(78)

G-8(≤ 50% J)

0.74±0.03

(47)

0.57±0.03

(31)

0.81±0.05

(30)

4.50±0.19

(30)

1.27±0.06

(50)

G-9 (>62.5 to75% J)

0.76±0.03

(98)

0.58±0.03

(81)

0.80±0.04

(83)

4.64±0.14

(81)

1.26±0.05

(100)

G-10 (>75% J)

0.70±0.03

(87)

0.58±0.03

(73)

0.80±0.04

(73)

4.46±0.15

(72)

1.20±0.05

(88)

Table 1 Least-squares means along with standard errors of persistency indices of milk production in relation to period of calving, parity, season of calving and genetic group in Jersey crossbred cattle

Figures in the parenthesis indicate number of observations Means with different superscripts in each subclass within a column differ significantly (P<0.05) from each other.

Conclusion

Different persistency indices of milk production of Jersey crossbred cattle were significantly affected by various environmental factors, which indicate the necessity of improving the managemental conditions of the farm for better productivity.

Acknowledgements

The authors are thankful to Director, ICAR-NDRI, Karnal and Head, ERS of ICAR-NDRI, Kalyani, India for providing necessary facilities for conducting this work. The help rendered by staff of cattle yard for maintaining and providing the records for this study is also duly acknowledged.