1 Ministry of Education Secondary Engagement Programme October
1 Ministry of Education Secondary Engagement Programme October 2020 Grade 9 Agricultural Science Week 4 Lesson # 2 Topic: Breed and Reproduction of Cattle Subtopic: Reproduction
Reproduction A good cow should calve once every year Sexual reproduction requires the following conditions to be met. (i) Puberty – Sexual maturity of both male and female (ii) Oestrous or Heat – Readiness of the female for the male (iii) Oestrous cycle – Interval between two Oestrous (iv) Ovulation – shedding of eggs by the ovary in the female (v) Ejaculation – shedding of sperms in the vagina by the male (vi) Fertilization – Union of the sperm and egg in the female reproductive tract (vii) Conception - union of the fertilized egg unto the wall of the uterus (placentation) (viii) Pregnancy or Gestation – Period of development of the foetus in the uterus or womb (ix) Parturition – act of giving birth 2
Time of Mating Heifers should be at least eighteen (18) months old at the time of first mating The heifer or cow will accept the bull during the oestrus period or heat The heat period lasts for about 12 -24 hours At this time, the animal exhibits both physical and behavioural changes Signs of heat are: - Restlessness - Bellowing - Mounting other animals and also allowing herself to be mounted - Loss of appetite - Swelling and reddening of the vulva - Milk production in lactating animal decreases 3
During the oestrus period, ovulation takes place twelve(12) after standing heat. The best time for mating the cow is about ten (10) hours after the end of standing heat Standing heat is when the female will stand to be mated by a male If the animal is not mated during oestrus or if conception does not take place, the cow return into heat/oestrus within 18 - 21 days The period between oestrus and the next is called the oestrus cycle 4
Pregnancy or Gestation Period - This is the period from conception to birth of the calf. - This period last between 280 - 282 days or about nine (9) months Signs of Pregnancy - The cow will settle down become quieter. - The cow will not demonstrate any sign of oestrus for the period - The cow belly will enlarge - If the cow is lactating, milk production will decrease. 5
Reproductive Cycle of the Cow Oestrous period: 12 – 24 hours Oestrous cycle : every 21 days Time of ovulation: 12 hours after heat Timing of mating: 10 hours after heat Gestation: 280 – 282 days 6
s e s i c the r e Ex ete h pl arc m Co rd se wo Q D F G V P U B E R T Y D G H J K O D A N C E S W A M E P W D O I J J K C O N C E P T I 7 O N M O O B C O D R F V N R A G H N T U T E R U S E F G V B N B U F O L H V T C N Y A A F H K N F C R WE E D F O N G D O J X H U F T N O I K T H U I M I T A Z I L I T R E F P Y S F L O G G V F B H Y J I J C V U L V A E I E U F U N I L L S M T A O N B M R B O R Q N D T W K A I T T L R L S G J K Y T E V E R H T W G E I S S G V O E J R U I U Y P A P P E T I M U Y O S R D T E I D T E N X H O H N J W G I T E B F Y S U F H J N L N I O T R R H G F D V A M E R A I F R L F U B I GF Q Q J O M I L K S M C I H O S T V Z O Y A F V MC O W L N S L P H E A T S N V C I B Z P L L D A D V H J K U I N D M K M P H Y S I R V N M U A F O A U O C A L H J K I E T T G V R U N M V E T O D E F A C B H L N M M L N G I B A Y A H J I N Y I U U T J I R B V G U U Y U A V N A C B N M T Y Y U I J M O L B R E E D I N G J T Y H J
Words Production Pregnancy* Milk Puberty* Conception* Heifers Ejaculation* Fertilization* Lactating* Vulva Appetite Breeding* Embryo Sexual Heat* Semen Ovulation* Parturition* Behavioural Sperms Birth Mounting Physical Cow Bull Development Union Foetus Ovary Uterus Ø Explain each term that is marked (*). 8
References Sahadeo Ragoonanan (2011) ‘Agriculture for CSEC Revision course’ New Edition, Caribbean Educational Publisher Ltd, Trinidad, WI Fitzroy Weever et al (2014) Agricultural Science for Secondary Schools in Guyana, Book 3, Ministry on Education NCERD, Georgetown, Guyana Sahadeo Ragoonanan (1991) CXC Agriculture- A Revision Course, Caribbean Educational Publisher Ltd, Trinidad, WI https: //www. youtube. com/watch? v=At. T 0 r. Lnm. BIE&featu re=youtu. be 9
- Slides: 9