Recuerde que puede expresar las dudas que hayan surgido
sobre este tema o cualquier otro por escrito al enviar las
actividades por correo.

Actividad
A
Read the following text carefully and do the exercises below:
(Lea el texto cuidadosamente y haga los ejercicios que se encuentran
debajo)
Protein: The dietary requirements of animals are not only a matter of
providing a sufficient quantity of protein. The quality of protein is also
important especially for monogastric animals. When ruminants are provided
with low quality protein, they can improve the quality of this protein due to
the activities of rumen microbes. Proteins are made from twenty-two amino
acids. Animals can only make about half of these amino acids; therefore,
they must be supplied with the nine they cannot make. There is no
difference at all in the nutritional value of amino acids whether (ya sea que)
they come from plant protein or animal protein, but some proteins do not
have a particular amino acid or have a very low percentage of it. Such
proteins are not satisfactory as an animal’s only source of protein and are
sometimes called “second class proteins”. They are better called “poor
quality” proteins. Thus, the protein in most grain contains low levels of the
amino acid lysine, while the protein zein in maize has a low percentage of
tryptophan; grain sorghum has almost no tryptophan. On the other hand,
most proteins of animal origin have larger amounts of essential amino acids.
Moreover, some plant proteins such as those of cottonseed meal and
soybeans have satisfactory levels of all essential amino acids.
Vitamins: These are essential nutrients which are needed in very small
amounts. Except for vitamin C, which is needed only by man and guinea pigs,
all vitamins are needed by animals. This does not mean that all vitamins
must be included in the diets for all animals.
Vitamin A: The substance carotene is a yellow pigment which occurs in
green leaves. Fig. 14.6 shows molecules of carotene and vitamin A which
clearly indicate that if you split one molecule of carotene in the centre; it
yields two molecules of vitamin A. In most animals, the conversion of
carotene into vitamin A takes place in the cells of the intestinal wall;
vitamin A passes through the wall into the blood stream. Synthetic vitamin
A is now available, but vitamin deficiencies in sheep and cattle are unlikely
to occur if animals have access to any green feed during the previous six
months. Unless poultry have access to green feed, they need vitamin A
supplements. Pigs do not generally need vitamin A supplements if they have
access to green grazing, lucerne meal or yellow maize.
(a. pp180/2, Understanding Farm Animals)
I.
Match the following concepts to the sentences below (there is not
a one-to-one correspondence)
1. probability
2. capacity
3. obligation
4. suggestion
a. When ruminants are provided with low quality protein, they can
improve the quality of this protein due to the activities of rumen
microbes. (2)
b. Animals can only make about half of these amino acids. (2)
c. they must be supplied with the nine (aminoacids). (3)
d. they cannot make. (2)
e. This does not mean that all vitamins must be included in the diets
for all animals. (3)
f. vitamin deficiencies in sheep and cattle are unlikely to occur if
animals have access to any green feed during the previous six
months. (1)
II.
translate these sentences
a. Cuando los rumiantes son provistos con baja calidad de
proteínas, ellos pueden aumentar la calidad de esas proteínas
con la actividad de los microbios ruminales.
b. Animales pueden solamente sintetizar cerca de la mitad de esos
aminoácidos.
c. Ellos deben ser suplementados con los nueve (aminoácidos).
d. Ellos no pueden hacerlos.
e. Esto no significa que todas las vitaminas deban incluirse en la
dieta de todos los animales.
f. Deficiencias vitamínica en ovinos y vacunos son improbable que
ocurran si los animales tienen acceso a alguna comida verde
durante los seis meses previos.
III.
answer the questions below in Spanish:
1. What is the difference in protein requirements between monogastric
animals and ruminants?
Los animales monogástricos deben recibir en su dieta proteínas de alta
calidad (que contengan aminoácidos esenciales) mientras que los
rumiantes toleran dietas con proteínas de pobre calidad debido a la
transformación por parte de los microorganismos ruminales.
2. Can animals manufacture their own amino acids?
Sí, pero no a todos.
3. Do all proteins have the same amino acids? How do plant and animal
proteins differ?
Las proteínas están compuestas por aminoácidos. Las proteínas de origen
animal contienen mayor cantidad de aminoácidos esenciales, mientras que
la proteína de origen vegetal es de menor calidad, excepto la proveniente
de la harina de la semilla de algodón y del poroto de soja.
4. Is it necessary to include all vitamins in a ration?
No es necesario que se incluyan todas las vitaminas en la dieta de todos
los animales.
5. Which is the source of vitamin A?
La fuente de vitamina A son las hojas verdes.
6. Is vitamin A essential for all animals?
Sí.