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Comparision of milk production and productive Life-Span between cows that were incorporated to herds from external sources and Local-Borned cows

Daniel Hojman1 and Ezra, Ephraim.2

1Ministry of Agriculture and Rural Development – Extension Service

2Israel Cattle Breeders Association – Herdbook Center

 

INTRODUCTION

Full production of the annual milk quota is one of the main factors that enable to achieve maximum profit by a dairy farm acting under Israeli conditions.

Times often, dairy farm managers come to a situation where the full production of the annual milk quota is compromised. In such cases the implementation of managerial practices that have the potential of increasing milk production –such as changes in the feeding plan, augmenting the number of daily milkings, shortening of the dry period- are usually considered. In conclusion, dairy farm managers tend to rely –in those situations- on managerial manipulations to the producing animals. They seldom consider the option of incorporating (purchasing) productive animals –milking cows or pregnant heifers- from external sources, although it is clear that this procedure would assure full production the annual milk quota without need for managerial changes (that may not provide the expected extra-milk yield)

The negative approach of dairy farms managers towards the incorporation of animals from external sources arouses from the supposition that “animals from external sources” may introduce “veterinarian problems” to the local herd or that will suffer from diseases that exist in the “absorbing” herd, which conduce to shortening the average productive life-span of the animals in the herd, in such a way that it turns the “incorporation” of the animals into a non-convenient step.

The objective of the present study was to compare milk yields and productive life-span of cows that were incorporated to herds from external sources, in relation to the existing local animals.

 

MATERIALS AND METHODS

Data were obtained from the Israeli Herdbook and included family dairy farms that in the time-period between 1994 and 2001 incorporated at least 2 cows per year, from external sources. The study considered the productive performance of the animals till year 2005. Cows were divided into two categories: animals purchased as heifers or as cows (at any moment after first calving). The examined parameters were average milk yield (corrected 305d lactations) and average productive life-span. The statistical model (SAS-GLM) included the following covariance factors: herd, year of calving, month of calving and lactation number.

From now on, the animals that were introduced to the herds from external sources will be called “External” and the animals that were in the local “absorbing” herds will be called “Local”.

 

RESULTS and DISCUSSION

Results for “Local” and “External” Heifers.
The data base included 14,395 lactations that occurred in 122 dairy herds: 10,680 lactations of “local” heifers and 3,715 lactations of “external” heifers.

The factors that were significant (P<0.05) in the two statistical analyses were herd, year of calving, month of calving and lactation number.

No significant difference was found regarding the average milk yields throughout lactations 1-4, between “local” and “external” heifers

No significant difference was found regarding average productive life-span in the herds between “local” and “external” heifers.

Results are presented in Table 1 (simple means) and in Table 2 (LSMeans).

 

Table 1. Number of lactations in the examined data-base, average milk yields (corrected 305d lactations, kg) and culling rate from herds for lactations 1-4 of “local” and “external” heifers.

 

“Local” Heifers “External” Heifers
Lact. Num. Number of Lactations Average Milk Yields Culling Rate   Number of Lactations Average Milk Yields Culling Rate
1 3,808 10,068 19.7 1,317 9,959 19.1
2 2,827 10,146 25.4 989 10,030 26.9
3 1,936 10,267 31.4 649 10,264 28.8
4 2,109 10,539 36.3 760 10,547 40.0

 

Table 2. LSMeans for milk yields (corrected 305d lactations, kg) and culling rate from herds for “local” and “external” heifers.

 

“Local” Heifers “External” Heifers

Significance

(P<0.05)

Milk Yields 10,085 10,067 ns
Culling Rate (%) 30.1 31.3 ns

 

Results for “Local” and “External” Cows.
The data base included 18,737 lactations that occurred in 140 dairy herds: 13,834 lactations of “local” cows and 4,904 lactations of “external” cows.

The factors that were significant (P<0.05) in the statistical analysis that examined milk yields were herd, year of calving, month of calving, lactation number and the source of the cows (“local” or “external”).

The factors that were significant (P<0.05) in the statistical analysis that examined productive life-span were herd, year of calving, month of calving and lactation number. No significant difference was found regarding average productive life-span in the herds between “local” and “external” cows.

Results are presented in Table 3 (simple means) and in Table 4 (LSMeans).

 

Table 3. Number of lactations in the examined data-base, average milk yields (corrected 305d lactations, kg) and culling rate from herds for lactations 1-4 of “local” and “external” cows.

 

“Local” Cows   “External” Cows
Lact. Num. Number of Lactations Average Milk Yields Culling Rate   Number of Lactations Average Milk Yields Culling Rate
1 3,762 9,882 20.4 694 9,965 16.0
2 3,393 9,860 28.2 1,028 9,970 28.1
3 2,632 9,953 30.9 1,041 10,110 29.9
4 4,047 9,954 44.2 2,141 10,116 43.1

 

Table 4. LSMeans for milk yields (corrected 305d lactations, kg) and culling rate from herds for “local” and “external” cows.

“Local” Cows “External” Cows

Significance

(P<0.05)

Milk Yields 9,912 10,003 0.01
Culling Rate (%) 33.4 32.4 ns

 

 

No significant differences were found in milk yields or productive life-span in herds between “local” and “external” heifers.

No significant differences were found in productive life-span in herds between “local” and “external” cows. “External” cows produced higher milk yields than “local” cows, which can be explained by the fact that the farmers that purchased cows from other herds they probably selected animals of higher genetic merit than the average local ones.

The findings of the present study show that dairy farmers must not be reluctant to consider the incorporation of animals from “external” sources to their herds. It must be strengthened that such operation must be done while performing the pertinent veterinarian checkings.

 

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