D. Plasse, H. Fossi and R. Hoogesteijn
The authors can be contacted at the Universidad Central de Venezuela,
Facultad de Ciencias Veterinarias, Apartado 2196, Maracay, Venezuela.
Acknowledgements. The authors wish to thank the owners, veterinarians, managers and
staff of the following ranches for their collaboration in collecting data: Estaci�n
Experimental La Cumaca, Estaci�n Experimental Calabozo, Cujicito, Guataparo, Jobito, La
Herrere�a, Los Ca�os, Los Gabanes, Mata de Agua, Matapalos, Merecure, San Pablo, Sta.
Luisa and Turagua. They gratefully acknowledge the revision of the manuscript by Professor
Lucia de Vaccaro.
The final processing of the data was supported by the Consejo de Desarrollo Cient�fico y
Human�stico of the Universidad Central de Venezuela through the Ayuda Institucional
No11-10-3720-96.
Afin d'�valuer les pertes de veaux entre le diagnostic de gravidit� et l'�ge de 18 mois, un jeu de donn�es de base comprenant 71 654 ann�es-vache provenant de 14 troupeaux participant � des programmes de recherche a �t� �tabli � partir de dossiers de production informatis�s. Le taux de gestation s'�levait � 71 pour cent et celui de perte pr�natale � 7,9 pour cent. Dans huit troupeaux, o� toutes les pertes de veaux �taient motiv�es par la mortalit�, 4,9 pour cent des 19 419 veaux n�s vivants sont morts avant le sevrage et 7,5 pour cent avant 18 mois. Dans six autres troupeaux, o� l'�valuation �tait moins pr�cise, 6,6 pour cent des 18 585 veaux n�s sont morts avant le sevrage et 12,3 pour cent avant 18 mois. Les pertes cumul�es entre la palpation et l'�ge de 18 mois s'�levaient � 17 pour cent. La mortalit� et la perte de vaches constat�es dans quatre troupeaux se situaient entre 1,2 et 4,1 pour cent. Dans six troupeaux, comptant 1 063 veaux morts, la fr�quence relative la plus �lev�e de mortalit� se produisait pendant les trois premiers jours de vie, mortalit� imputable essentiellement � la malnutrition et � la faiblesse, mais �galement � d'autres raisons. Sur l'ensemble des animaux perdus, 71,3 pour cent sont morts avant le sevrage et le reste entre le sevrage et 18 mois. Sur une base annuelle, pour chaque 100 vaches faisant l'objet de l'�tude, on a constat� 70 gestations, 64 veaux n�s vivants, 61 veaux sevr�s et 58 vivants � l'�ge de 18 mois.
Con el fin de evaluar la p�rdida de terneros entre el diagn�stico de pre�ez y la edad de 18 meses, se construy�, a partir de registros de producci�n computarizados, una base de datos de 71 654 vacas-a�os de 14 reba�os participantes en programas de investigaci�n. El porcentaje de pre�ez fue del 71 por ciento y la p�rdida prenatal del 7,9 por ciento. En ocho reba�os, en los cuales toda la p�rdida fue explicada por mortalidad, el 4,9 por ciento de 19 419 terneros nacidos vivos murieron antes del destete y el 7,5 antes de los 18 meses de edad. En otros 6 reba�os con evaluaci�n menos exacta, se perdi� el 6,6 por ciento de los 18 585 terneros nacidos antes del destete y el 12,3 por ciento hasta la edad de 18 meses. La p�rdida acumulada entre la palpaci�n y 18 meses fue del 17 por ciento. La mortalidad y p�rdida de vacas en cuatro reba�os fue entre el 1,2 y el 4,1 por ciento. En seis reba�os con 1 063 terneros, la mayor frecuencia relativa de mortalidad ocurri� durante los primeros tres d�as de vida y fue debida mayormente a desnutrici�n y debilidad pero tambi�n a otras razones. De todos los animales perdidos, el 71,3 por ciento murieron antes del destete y los restantes durante el per�odo postdestete. Anualmente, cada 100 vacas en el estudio produjeron 70 pre�eces, 64 terneros nacidos vivos, 61 destetados y 58 vivos a la edad de 18 meses.
High pregnancy percentages and low mortality rates are decisive factors determining the profitability of beef cattle production because they directly determine the number of animals available for sale and indirectly the genetic progress that may be achieved.
Low productivity of tropical beef cattle populations in Latin America is
generally attributed to low reproductive efficiency, high mortality and low growth rates.
However, data on death losses during different phases of life are scarce and future
improvement programmes require better documentation of this trait.
The objective of this paper is therefore to summarize, as a series of case studies, the
available data on mortality in tropical beef cattle derived from genetic research
programmes in Venezuela.
Computerized production data from 14 herds (A to N) in two experiment stations (A and B) and 12 private farms cooperating in genetic research programmes carried out over 27 years (1965-1991) were used. The data form a scientifically reliable subset of 276 484 records from 22 herds presented in a practical discussion of the theme by Plasse et al. (1993). Additionally, two commercial Zebu herds, 0 and P, were only used for cow loss evaluation.
The herds are located in seven states of Venezuela under a variety of
environmental conditions and they are a fair representation of the main beef cattle
production areas of the country. Only herds with complete and reliable records were taken
into consideration. For each one, experimental genetic and non-genetic improvement
programmes were designed at the beginning of the research programme. They were supervised
by technical personnel and the authors. Each herd had veterinary assistance.
Herds A to N were composed of either registered Brahman, Nellore or Guzerat cows or
non-registered �lite cows of these breeds, Criollo and Bos taurus x Bos indicus
cross-breeds, and produced bulls for use on the ranch or for sale.
The herds were subjected to one of two types of breeding season lasting four to five
months: i) for calving at the end of the dry season and beginning of the rainy season in
all ranches with higher non-flooded grassland; and ii) for starting to calve at the
beginning of the dry season in areas with flooded savannahs. Pregnancy diagnosis was
carried out by a veterinarian 45 to 60 days after the end of the breeding season. Calving
took place in special pastures and calves were tattooed and weighed within 24 hours after
birth. They were later branded with individual identification numbers. Calves stayed with
their dams on pasture without supplemental feed except a mineral mixture, which was
offered to all animals. Weaning took place at seven to eight months.
Herds A, C, D and G were maintained on cultivated pasture and herds J, K, M and N were
kept on native savannah. In the others, weaners were maintained until 18 months on
cultivated pasture and the rest of the time they spent on native grass, as did all other
animals. The female calves of all herds were vaccinated against brucellosis and yearly
follow-up tests were carried out. The first outbreak of leptospirosis was diagnosed in
1968 in herd A. As a result of the increase of abortions during the 1970s, most of the
ranches introduced testing and vaccination for leptospirosis. Those with a high incidence
of abortions also carried out vibriosis and IBR diagnostic tests with positive results. In
more recent years, vaccination programmes against vibriosis were adopted by most of the
ranches. No vaccinations were carried out against IBR because vaccines were not available.
No trichomoniasis was diagnosed.
In this paper, mortality was determined for the following phases: (1) from pregnancy
diagnosis to birth; (2) from birth to weaning; (3) from weaning to 18 months; and (4) for
females in the breeding herd (yearly). In phase (1), abortions were observed by ranch
personnel. Cows diagnosed pregnant, but which did not give birth to a live calf, were
classified as having lost their conceptus. The sum of both incidents was defined as
"prenatal loss". For phases (2) and (3) the material was subdivided into data
sets I and II. The former corresponded to herds where all losses were proved to be caused
by death, while data set II included those where extensive conditions made it impossible
to determine the fate of every missing calf. Thus, losses were classified as death
(proved) and "other losses". A calf in the latter classification might have
died, but might also have been stolen, escaped to another herd, etc. However, in each case
this represented an economic loss.
For six herds from data set I, age and cause of death were regularly recorded for the
periods: < three days, four to 30 days and 31 days to weaning as being due to
"undernutrition and/or weakness" or "other reasons"; and for the
postweaning phase as "disease" or "other reasons". This classification
was intended to separate the causes resulting from maternal effects (undernutrition of the
calf) from the others.
Data on cow mortality were reported from herds A, H+O, J and P.
Table 1 presents prenatal loss in the 14 herds recorded over an average of 8.7 years. The mean pregnancy rate of 71 654 cow-years was 71 percent, which is high for the Latin American tropics. The lowest value, 57.2 percent, was obtained in a herd on low savannah and the highest, 81.8 percent, on cultivated pasture in a more favourable area.
1
Prenatal losses in 14 Venezuelan herds
Pertes pr�natales dans 14 troupeaux au Venezuela
P�rdidas prenatales en 14 reba�os de Venezuela
Herd |
State |
Years (No.) |
Breed1 |
Cows palpated |
Cows pregnant (No.)2 |
Observed abortions (%)3 |
Pregnant non-calving cows4 (%)3 |
Total prenatal loss (%)3 |
A |
Yaracuy |
10 |
RB |
1 906 |
72.0 |
4.0 |
1.5 |
5 |
B |
Gu�rico |
17 |
RB, EB, CR, XX |
6 398 |
70.4 |
2.7 |
3.0 |
5.7 |
C |
Portuguesa |
24 |
RB |
7 501 |
72.8 |
2.9 |
5.0 |
7.9 |
D |
Carabobo |
10 |
RB, RN, RG |
2 159 |
81.8 |
2.3 |
1.0 |
3.3 |
E |
Gu�rico |
9 |
RB, RN, RG |
12 335 |
71.4 |
...5 |
5.5 |
5.5 |
F |
Cojedes |
5 |
RB |
755 |
64.7 |
0.9 |
6.3 |
7.5 |
G |
Cojedes |
4 |
EB, XX |
4 821 |
80.6 |
0.6 |
3.9 |
4.4 |
H |
Apure |
6 |
RB, EB, XX |
6 160 |
80.4 |
2.0 |
5.7 |
7.7 |
I |
Barinas |
5 |
EB, XX |
3 215 |
71.8 |
1.3 |
7.6 |
8.9 |
J |
Apure |
6 |
RB |
2 549 |
74.6 |
1.8 |
6.9 |
8.8 |
K |
Apure |
5 |
ES |
5 181 |
64.4 |
1.16 |
9.6 |
10.6 |
L |
Apure |
8 |
EN, EB, EG |
12 919 |
65.3 |
0.6 |
12.6 |
13.1 |
M |
Apure |
8 |
EB |
4 410 |
66.0 |
4.3 |
3.7 |
8.0 |
N |
Apure |
5 |
EG, EB |
1 345 |
57.2 |
4.5 |
4.7 |
9.4 |
Total (14 herds) |
71 654 |
71.0 |
1.6 |
6.3 |
7.9 |
1 RB = Registered Brahman; EG = Elite Guzerat; EB = Elite
Brahman; RN = Registered Nellore; CR = Criollo; RG = Registered Guzerat; EN = Elite
Nellore; XX = Bos taurus x Bos indicus.
2 In relation to palpated cows.
3 In relation to pregnant cows.
4 Non-observed losses.
5 Not recorded.
6 Observations made only during the last years.
Mean prenatal loss was 7.9 percent and varied between extreme herds from
3.3 to 13.1 percent. Annual variation within herds was as high as 2.3 to 16.2 percent in
herd A. The mean of 7.9 percent for prenatal loss is composed of 1.6 percent observed
abortions and 6.3 percent cows diagnosed pregnant but which did not calve. This means that
only 20.3 percent of all losses were explained by a reported abortion. It is apparently
impossible to draw conclusions about prenatal loss in beef cattle herds by only taking
into consideration the observed abortions, since many foetuses are likely to be taken away
by wild animals before they can be recorded. Also, early losses might result from
absorption. This emphasizes the importance of pregnancy monitoring and strict recording of
parturition.
The lowest prenatal loss was recorded in the herd with the highest pregnancy percentage
(D) and the highest value corresponded to a herd with a relatively low reproductive
efficiency (L). The correlation between the mean pregnancy percentages and prenatal losses
of the 14 herds was -0.63 (P<0.05), which suggests that, to a certain extent, the same
factors that produce high death losses between palpation and parturition also affect
pregnancy percentages negatively. Cows which conceived at the beginning of the four to
five months breeding season already had gestations of 5.5 to 6.5 months when they were
palpated. This type of evaluation therefore underestimates the real loss, since open cows
may have been pregnant and aborted before palpation. Thus, part of the real loss might
reflect itself in a lowered pregnancy percentage. Also, cows diagnosed pregnant might have
lost a foetus conceived earlier and then conceived again. In Venezuelan Bos indicus cows,
Linares and Rodr�guez (1983) found a 12.5 percent prenatal loss, most of which occurred
in the fifth to seventh month of gestation. In the same area, Hoogesteijn et al. (1983a)
found a 17 percent prenatal loss in four extensively managed Zebu herds. A survey study in
Brazil, Colombia and Venezuela found prenatal death rates of 8, 14 and 16 percent (Vera
and Ser�, 1985). In the Beni, Bolivia, prenatal losses of 5.3 percent were found in a
Criollo and a Zebu herd (Verde et al., 1993; Plasse, Fossi and Hoogesteijn, 1993).
Our values do not seem excessively high since Australian workers reported 6 to 40 percent
losses between palpation and the age of three to four months of the calf (Donaldson,
Ritson and Copeman, 1967; Lamond, 1969; Young and Blair, 1974).
According to diagnostic results in most of the herds, the main causes of prenatal loss
were leptospirosis and vibriosis. Although the majority of the herds followed vaccination
programmes and some were successful in lowering the loss from over 20 to 5 percent or
less, others did not have the desired results. We believe that, in some cases, problems in
the refrigeration chain, owing to inappropriate transport and storage between laboratory
and field, might have lowered the effectiveness of the vaccine; in other cases, that the
vaccination programmes were not properly carried out.
Some herds were relatively small and were maintained on cultivated
pasture under more intensive management ...
Certains troupeaux �taient maintenus sur des p�turages cultiv�s, de taille relativement
faible et g�r�s de mani�re plus intensive...
Unos reba�os relativamente peque�os, manejados m�s intensivamente, fueron mantenidos en
pasto cultivado...
... while others were large, less intensively managed and maintained
on savannah
... tandis que d'autres �taient importants, avec une conduite moins intensive et
maintenus sur la savane
... mientras que otros reba�os grandes, manejados menos intensivamente, fueron mantenidos
en sabana
Photos/Fotos: D. Plasse
In eight intensively managed herds, evaluated during an average of 9.3 years, all calf losses were explained by mortality (Table 2). Of 19 419 calves born alive, 4.9 percent died before weaning, with a variation between herds from 2.4 to 11.5 percent. Annual within herd variation was as high as 1.5 to 22.1 percent in herd A and as low as 2.3 to 3.4 percent in herd G. In general, a low annual variation was characteristic of herds with a low mean mortality and a high yearly variation was usual for those with high averages.
2
Preweaning, postweaning and total calf mortality in eight Venezuelan herds (data set I)1
Mortalit� des veaux avant sevrage, apr�s sevrage et mortalit� totale (jeu de donn�es
I)
Mortalidad predestete, postdestete y total de terneros en ocho reba�os de Venezuela (lote
I)
Death loss |
||||||
Herd |
Years |
Calves born alive |
Calves weaned |
Birth - |
Weaning - |
Total birth - |
A |
11 |
1 384 |
1 293 |
6.6 |
2.3 |
8.7 |
B |
12 |
2 460 |
2 312 |
6.0 |
6.0 |
11.7 |
C |
24 |
5 050 |
4 692 |
7.1 |
2.0 |
8.9 |
D |
10 |
1 560 |
1 522 |
2.4 |
0.6 |
3.0 |
E |
4 |
4 270 |
4 170 |
2.4 |
2.5 |
4.8 |
F |
4 |
339 |
300 |
11.5 |
3.0 |
14.2 |
G |
3 |
2 729 |
2 650 |
2.9 |
1.4 |
4.3 |
J |
6 |
1 625 |
1 534 |
5.6 |
1.5 |
7.1 |
Total (8 herds) |
9.3 |
19 419 |
18 473 |
4.9 |
2.4 |
7.5 |
1 For location and breeds see Table 1.
2 In relation to calves born alive.
3 In relation to weaned calves.
In six other herds evaluated during an average of 6.2 years (Table 3), not all calves born alive but absent at weaning were recorded as dead and losses were classified as either: i) calves reported dead; and ii) calves lost without a precise cause (dead, lost, stolen). Mean mortality was 5.3 percent and the average of other losses 1.3 percent, giving a total preweaning loss of 6.6 percent.
3
Preweaning, postweaning and total calf mortality and loss in six Venezuelan herds (data
set II)1
Mortalit� et perte de veaux avant sevrage, apr�s sevrage et totalit� dans six troupeaux
v�n�zu�liens (jeu de donn�es II)
Mortalidad y p�rdida predestete, postdestete y total de terneros en seis reba�os
venezolanos (lote II)
Birth - weaning |
Weaning - 18 mths |
|||||||||
Herd |
Years |
Calves born alive |
Calves weaned |
Mortality2 |
Other losses4 |
Total preweaning loss |
Mortality2 |
Other losses4 |
Total postweaning loss |
Total loss birth - |
H |
6 |
3 932 |
3 645 |
5.3 |
2.0 |
7.3 |
0.5 |
3.6 |
4.2 |
11.2 |
I |
4 |
1 544 |
1 416 |
3.1 |
5.2 |
8.3 |
2.0 |
7.3 |
9.4 |
16.9 |
K |
5 |
2 815 |
2 590 |
5.9 |
2.1 |
8.0 |
4.5 |
5.8 |
10.3 |
17.5 |
L |
8 |
6 882 |
6 508 |
5.3 |
0.4 |
5.7 |
2.2 |
3.4 |
5.6 |
10.8 |
M |
8 |
2 633 |
2 472 |
6.1 |
0.0 |
6.1 |
2.1 |
2.8 |
4.9 |
10.7 |
N |
6 |
779 |
726 |
7.3 |
0.0 |
7.3 |
1.1 |
1.4 |
2.5 |
9.1 |
Total (6 herds) 6.2 |
18 585 |
17 357 |
5.3 |
1.3 |
6.6 |
2.1 |
4.0 |
6.1 |
12.3 |
1 For location and breeds, see Table 1.
2 Diagnosed death.
3 In relation to calves born alive.
4 Missing but death not reported.
5 In relation to calves weaned.
Our values for preweaning mortality and total loss of 4.9 and 6.6 percent in data sets I and II, respectively, are lower than those reported in the literature from tropical Latin America where 21 herds with 58 079 live-born calves averaged 7.8 percent (Table 4) and also less than the 9 percent preweaning mortality reported by Cundiff, Gregory and Koch (1982) from 24 experiments in the United States.
4
Preweaning mortality in tropical Latin America
Mortalit� apr�s sevrage en Am�rique latine tropicale
Mortalidad prenatal en Am�rica Latina tropical
Location |
Breed |
Calves born |
Mortality |
Reference |
Brazil, S�o Paulo |
lndubrasil |
13 760 |
7.0 |
Barros et al., 1972 |
Mexico, San Luis Potosi |
Brahman |
1 569 |
5.1 |
Rodr�guez & Escrib�, 1972 |
Venezuela, Anzo�tegui |
Crosses Bos taurus x Bos indicus |
849 |
13.5 |
Montoni, Gonz�lez-Crespo & Verde, 1979 |
Venezuela |
Brahman |
5.3 |
Ord��ez, Bastardo & Plasse,1979 |
|
- Llanos Altos |
Brahman |
4 905 |
4.1 |
Ord��ez, Bastardo &
Plasse,1979 |
Venezuela, Apure |
Brahman |
|
8.0 |
Hoogesteijn et al., 1983b |
Colombia, Meta |
Brahman |
|
|
|
Colombia, C�rdoba |
Brahman, Criollo Romosinuano, crosses |
1 561 |
7.4 |
Hern�ndez in FAO, 1981 |
Colombia, Antioqu�a |
Brahman, Criollo BON, crosses |
676 |
4.0 |
Hern�ndez in FAO, 1981 |
Venezuela, Monagas |
Brahman and Charolais, |
1 441 |
11.7 |
Par�s, Gonz�lez & Verde, 1983 |
Costa Rica, Pacifico Seco |
Brahman |
2 674 |
9.4 |
Chan et al., 1986 |
Brazil, Par� |
Nellore |
12 112 |
5.1 |
Hautle, 1987 |
Mexico, Tamaulipas |
Brahman |
771 |
7.0 |
Gonz�lez & Segura, 1989 |
Venezuela, T�chira |
Brahman |
918 |
9.0 |
Montoni, Rojas & Mago de Montoni, 1996 |
Venezuela, Portuguesa |
1/2 Bos taurus1,
1/2 Brahman, |
|
10.0 |
Mart�nez & Gabald�n,
1990 |
Bolivia, Beni |
Zebu |
6 312 |
3.3 |
Galdo et al., 1992 |
Bolivia, Beni |
Criollo Yacumeno |
7 334 |
5.1 |
Bauer et al., 1992 |
Unweighted mean of 21 values |
58 079 |
7.8 |
1 Charolais and Simmental.
Registration at birth and daily supervision of the newly born calf
are means to monitor abortion and early calf loss. In the photo: Criollo at Beni, Bolivia
L'enregistrement � la naissance et la surveillance journali�re du veau nouveau-n� sont
des mesures qui permettent de surveiller les risques d'avortement et la perte pr�coce de
veaux (Criollo � Beni, Bolivie)
El registro al nacimiento y la supervisi�n del reci�n nacido son medidas para monitorear
abortos y p�rdidas tempranas en los becerros (Criollo en Beni, Bolivia)
Good maternal ability is important for survival of the calf
Une bonne aptitude maternelle est importante pour la survie du veau
Una buena habilidad materna es importante para la sobrevivencia del becerro
Photos/Fotos: D. Plasse
Death loss between weaning and 18 months in data set I was 2.4 percent (Table 2) with extreme values between herds of 0.6 to 6.0 percent. The latter value corresponds to an experimental herd where the mean was influenced by high mortality in Criollo (Bos taurus) and 3/4 Bos taurus 1/4 Bos indicus cattle. In data set II (Table 3) postweaning mortality and other losses were on average 2.1 and 4.0 percent, respectively, for a total of 6.1 percent. Yearly within herd variation was as high as 1.8 to 21.2 (herd H) and as low as 0.7 to 3.9 percent (herd N). The range of values between herds was from 2.5 to 10.3 percent.
The accumulated loss up to birth, weaning and 18 months in 35 976 calves detected alive initially by palpation of the dams was 8.6, 13.6 and 17 percent, respectively, and prenatal loss was responsible for 51 percent of the total (Table 5). The majority of these values are higher than those reported in a Zebu herd in the savannah of the Beni, Bolivia, which were 5.3, 9.5 and 14.2 percent (Plasse, Fossi and Hoogesteijn, 1993) and in a Criollo herd at the same location, where corresponding losses were 5.3, 10 and 20.9 percent (Verde et al., 1993). However, Bellows and Short (1994) showed a 15 percent loss between pregnancy diagnosis and weaning in a large data set from the United States. Our data indicate that, for each 100 cows palpated, 70 were pregnant, 64 calved, 61 weaned a calf and 58 had offspring which were alive at 18 months of age. In the herd with best results (D) these values reached 81, 78, 76 and 76, respectively, while in the worst one (K) they were 62, 56, 52 and 47.
5
Accumulated loss at birth, weaning and eighteen months1
Pertes cumul�es � la naissance, au sevrage et � 18 mois
P�rdida acumulada al nacimiento, destete y a los 18 meses
Cows |
Accumulated calf
loss (%)2 |
||||||
Herd |
Years |
Palpated |
Pregnant |
Birth |
Weaning |
18 mths |
Prenatal loss as |
A |
10 |
1 906 |
1 372 |
5.5 |
11.3 |
13.4 |
41 |
C |
24 |
7 501 |
5 461 |
7.9 |
14.4 |
16.1 |
49 |
D |
8 |
1 685 |
1 358 |
3.4 |
5.6 |
6.2 |
55 |
E |
4 |
6 275 |
4 530 |
5.8 |
8.0 |
10.3 |
56 |
F |
4 |
573 |
368 |
7.9 |
18.5 |
20.9 |
38 |
G |
3 |
3 483 |
2 843 |
4.0 |
6.9 |
7.6 |
53 |
H |
5 |
4 803 |
3 780 |
8.0 |
16.5 |
18.4 |
44 |
I |
4 |
2 467 |
1 708 |
9.9 |
14.6 |
22.4 |
44 |
J |
5 |
2 149 |
1 576 |
8.6 |
13.4 |
14.6 |
59 |
K |
4 |
4 042 |
2 523 |
10.3 |
17.0 |
25.4 |
41 |
L |
7 |
11 074 |
7 213 |
13.7 |
18.0 |
23.1 |
59 |
M |
7 |
3 823 |
2 475 |
8.3 |
14.2 |
17.8 |
47 |
N |
5 |
1 345 |
769 |
9.4 |
15.6 |
17.9 |
53 |
Total herds |
136.9 |
51 126 |
35 976 |
8.6 |
13.6 |
17.0 |
51 |
1 For location and breed see Table 1.
2 In relation to potential calves palpated.
The highest relative frequency of death occurred during the first three days of life (Table 6) and the number of deaths per unit of time decreased with increasing age of the calf. In early life, "undernutrition and weakness" of the calf was a more important cause than "other reasons", showing the influence of maternal ability at this age. After the first month, "other reasons" gained importance increasingly. While 71.3 percent of all deaths occurred in the preweaning phase, 28.7 percent of the dead calves were lost after weaning, when "diseases" and "other reasons" were of similar proportion.
6
Cause of death in six Venezuelan herds1
Causes de mortalit� dans six troupeaux v�n�zu�liens
Causas de mortalidad en seis reba�os de Venezuela
Preweaning mortality |
Postweaning mortality |
|||||||||
Herd |
Years |
Total dead calves |
�3 days: Undernutriton ad
weakness |
�3 days: Other reasons |
4-31 days: Undernutriton ad
weakness |
4-31 days: Other reasons |
31 days to weaning:
Undernutrition |
31 days weaning: Other reasons |
Disease |
Other reasons |
A |
11 |
121 |
2.5 |
11.6 |
15.7 |
19.8 |
7.4 |
18.2 |
14.1 |
10.7 |
B |
12 |
287 |
15.3 |
6.6 |
8.7 |
5.9 |
1.0 |
13.9 |
32.5 |
16.0 |
C |
24 |
458 |
6.8 |
7.2 |
10.3 |
14.7 |
8.6 |
32.0 |
9.4 |
11.0 |
D |
10 |
47 |
12.8 |
0.0 |
0.0 |
8.5 |
2.1 |
57.5 |
8.5 |
10.6 |
G |
3 |
43 |
4.7 |
4.7 |
14.0 |
9.1 |
0.0 |
34.9 |
7.0 |
25.6 |
J |
6 |
114 |
9.7 |
9.7 |
14.0 |
8.8 |
8.8 |
28.9 |
6.1 |
14.0 |
6 herds |
11 |
1 070 |
9.1 |
7.4 |
10.5 |
11.9 |
5.8 |
26.6 |
15.5 |
13.2 |
1 See Table I for location and breeds.
2 In relation to total number of dead.
The high relative frequency of deaths during the first three days of life
in tropical cattle seems to have two main reasons: very low birth weights and deficient
maternal ability (including udder problems). In a study on the behaviour of cow-calf
pairs, Beltr�n (1976) found that 10 percent of the calves born required human help for
suckling. All calves that died within the first three days after birth weighed less than
20 kg. This relation between low birth weight and early mortality was also shown by Koger et
al. (1967), Par�s, Gonz�lez and Verde (1983) and Montoni, Rojas and Mago de Montoni
(1996).
Management and health programmes are of basic importance in improving calf survival. This
was evident when Beltr�n (1976) initiated a research project to detect causes of high
preweaning mortality after a four-year average of 12.6 percent was found in herd A. During
the five years of this study, death loss dropped to 3.9 percent and increased again to 5
percent in the two years afterwards. It can be concluded that the daily observations and
the increased attention to cows and calves during the experiment had a positive influence
on calf survival. A similar experience was published by Montoni, Rojas and Mago de Montini
(1996), who found that an economic stimulus for the cowhands had a positive influence on
preweaning survival. These workers estimated that 51 percent of their preweaning death
rate (9 percent) could have been avoided.
The season of birth is important for calf survival. In the tropics, higher mortality is
found in calves born in the rainy season compared with those born in the dry season
(Rodr�guez and Escriv�, 1972; Ord��ez, Bastardo and Plasse, 1979; Camacho et al.,
1983; Montoni, Rojas and Mago de Montoni, 1996).
Breed composition also has an influence on mortality. In herd B, pure-bred Criollo had the
highest death rate between birth and 18 months followed by 3/4 Bos taurus 1/4
Brahman calves while Brahman and 3/4 Brahman-1/4 Bos taurus had the lowest values
(Ocanto et al., 1986; Plasse, et al., 1986).
On savannah, cows will walk long distances to graze. They leave
their calves in a "nursery", where other dams take turns in caring for them
Dans la savane, les vaches parcourent de longues distances pour p�turer. Elles laissent
leurs veaux dans une �garderie�, o� ils sont tour � tour surveill�s par d'autres
femelles reproductrices
En la sabana las vacas caminan largas distancias para pastorear, y dejan sus becerros en
una �guarder�a infantil� donde otras madres se turnan para cuidarlos
Photo/Foto: D. Plasse
Abortion and death during the first months are the most important
causes of low production per cow
L'avortement et la mortalit� pendant les premiers mois sont les principales causes de la
faible production par vache
Los abortos y la mortalidad durante los primeros meses son causas muy importantes de la
baja producci�n por vaca
Photo/Foto: D. Plasse
A Zebu herd in the Venezuelan savannah
Un troupeau de z�bus dans la savane v�n�zu�lienne
Un reba�o ceb� en la sabana venezolana
Photo/Foto: D. Plasse
In four herds with a total of 97 374 cow-years, the mean cow mortality and loss was 3 percent (Table 7). The values of herds A, H+O and J were due to mortality alone and comparable with the 1 to 2 percent reported by O'Rourke et al. (1995) from northern Australia. In herd P, loss from stealing contributed to the relatively high value. However, the higher mortality in this herd could also be explained by botulism (N. M�rquez, personal communication) and by the high proportion of old cows. Culling of old cows, vaccination against botulism and better inventory control in this very large cattle ranch lowered the loss between 1990 and 1992 from 5.6 to 2.9 percent.
7
Mortality and other losses in cows in four Venezuelan herds
Mortalit� et autres pertes de vaches dans quatre troupeaux v�n�zu�liens
Mortalidad y otras p�rdidas de vacas en cuatro reba�os de Venezuela
Herd |
State |
Years |
Breed1 |
Cow-years |
Cow mortality |
A |
Yaracuy |
12 |
RB |
2 320 |
1.4 |
H+O |
Apure |
7 |
RB, CB, XX |
31 900 |
1.2 |
J |
Apure |
6 |
EB |
3 099 |
2.0 |
P |
Apure |
7 |
CB |
60 055 |
4.1 |
Total (4 herds) |
|
8.0 |
97 374 |
3.0 |
1 RB = Registered Brahman; EB = Elite Brahman; CB = Commercial
Brahman; XX = Bos taurus x Bos indicus.
2 In relation to cows palpated the previous year.
High mortality between pregnancy diagnosis and the age of 18 months was clearly demonstrated by this study and can be considered to be one of the primary reasons for low productivity of beef cattle herds in Venezuela, as well as in the Latin American tropics in general. It must be emphasized that the herds evaluated were all managed under technical supervision and it must be assumed that their production level is above that of average herds in the country, which are estimated to have a pregnancy percentage of around 50 percent and a higher mortality rate than found here (Plasse, 1992). High prenatal losses of 7.9 percent were responsible for 51 percent of the total. Although some herds had good results from their leptospirosis and vibriosis vaccination programmes, in most cases the results have been rather disappointing. Probable reasons may include the reluctance of the cattle breeders to carry out intensive vaccination programmes persistently, the difficulty of acquiring good-quality vaccines and the involvement of other non-controlled virus diseases. On a national level, lack of sufficient information and education on reproductive diseases, combined with the near collapse of the official sanitary sector have hindered progress in the solution of the problem. On the other hand, the large variation between herds in this study indicates that considerable improvement is possible on most of the ranches. However, our values still underestimate the loss during gestation for reasons discussed above. A large proportion of prenatal death is not expressed in our figures but occurs before palpation and influences pregnancy rate rather than loss as defined in this paper. According to Bellows and Short (1994), early embryonic death is quite high in beef cattle, including tropical breeds (Plasse, Warnick and Koger, 1970).
Our values of preweaning and postweaning mortality are lower than those
given in the literature, but the large variation between herds indicates that it can still
be improved by better management, stricter inventory control and more intensive management
and health programmes as well as by culling cows with low maternal ability.
The mean total loss between pregnancy diagnosis and the age of 18 months was 17 percent,
which is very high. Variation between herds ranged from 6.2 to 25.4 percent and indicates
that there is ample opportunity for improvement.
In our opinion, it is essential to inform the cattle industry about the magnitude of these
problems and offer available technology for their solution. Government agencies,
universities, veterinary associations and private technical assistance groups must
cooperate with cattle breeders to lower the heavy losses from death and other causes.
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